There's a lot to unpack here. First off I was probably a bit too snarky in my last response. So apologies for that.
Ships being sunk by missiles - I can't do much about time scales and examples. Aside from tests we simply have no other examples to draw upon since there haven't been any other examples to draw upon. The fact that Argentinians imported French aircraft and missiles to sink English frigates can't be helped (nor can the irony). Exocets were deadly then, and are deadly today with all their upgrades. Further details are still needed for the sinking of the Moskva, but the fact that a pair of missiles sunk a cruiser that had been refitted with up to date Russian ECM/ECCM, countermeasures and CIWS systems stands on it's own. The question about the state of the systems at the time of the attack would be no different for ships in the 52nd century. Since its an equivalency across the centuries, it's a moot point. The Neptune is essentially a reverse-engineered KH-35 missile. The KH-35 is about 20yrs old. Neptunes are only a few years old and only recently entered service. The issue of a ship moving in only 2 dimensions is point, but not especially valid. The Neptune is a sea-skimming missile that moves essentially in the same dimensions (i.e it's not making large or rapid changes in it's altitude). If we translated this to space then both target and missile would be able to maneuver in 3-D, so again it's a matter of equivalency. Velocities of the target and the missile could be factors - but you'd have to provide relative speeds AND maneuverability of each in order to argue pro's or con's. A fast moving large target that is not agile is still a fast moving target. Whichever of the two has the greater ability to change course/heading is going to win the dodging game.
Costs for attackers/defenders This is an interesting argument. At the highest level, losing is the ultimate cost. Then comes how much each side is investing in their own defense, and after that what their relative costs are. For the sake of comparison we'll have to assume all relative costs of production and procurement are equal. And that all sides are willing and able to spend for their own defense. That just leaves how many credits an attacker would need to expend to take out a defender. We already know from our own reality that nations are willing to expend on their defense. To what extend depends upon the nations' capabilities. The US was willing to spend heavily to protect a carrier battle group. Aegis radars cost $1 billion dollars per platform (at the time of their launch). A single Phoenix AAM cost abou $500k and a Tomcat carried 6 of them. Then there was the cost of an SM-2 missile - a Tico-class cruiser carried almost 70 of them. The frigates and destroyers in the battle group carried more. The Soviets desire was to overwhelm the defenses through air, surface and sub-surface launched missiles. The cost of a missile capable of being launched at a distance (so your launching platforms have a fair chance of survival) is going to be roughly the cost of the counter-missile. It's not really practical to compare Soviet and US costs for a variety of reasons. The cost of a missile swarm (and protecting against it) is inconsequential because both the USN and Soviet sides DID actually spend the money to create the capabilities to do so AND to protect against it. To date, however, it's only theoretical since we didn't go to war. As you correctly point out, they were [GAMED] by both sides. And, as facts point out, both sides expended vast sums because they felt that it was needed in order to accomplish the mission - that of eliminating (or protecting) your carrier battle groups. The only thing that would remain debatable is which side may have come out of the simulated combat and still be able to perform their mission. No nation has ever performed this except in simulations. And since both sides have continued to invest heavily in newer and more modern systems, I would say that each side still believes it is possible (however improbable).
Transition away from big-gun ships to aircraft and missiles I think you missed the point about the transition away from guns to aircraft and missiles as the primary way for naval craft to fight with one another. Carrier borne aircraft DID put an end to the era of big guns, as evidenced by the combat that took place during WW2. There were very few instances of surface fleets engaging each other with only shipboard guns. Pretty much every fleet action in WW2 was with aircraft and not guns - though there are some interesting and notable exceptions. Once aircraft proved that they were able to project power and sink surface vessels, they became the primary ways to project power at sea. And yes, they did so through guns, bombs and torpedoes. I don't know what point you are trying to make mentioning curvature, gravity and the inability to shoot through the planet. Both ballistic and direct-fire trajectories accomplish the same thing - delivering your payload to the target. Whether it's done 2D or 3D is irrelevant. The only things that matter is that your offensive projection ability exceeds the targets defensive capabilities and you are able to cause damage to your target. To what extent you feel the need to "drive home" curvature is something that you will have to explain further. I don't see the relevancy. The point of any attack (gun, beam or missile) is to affect the target - exactly HOW it gets there doesn't really matter. Laser weaponry can be affected by sand, by anti-laser aerosol, etc, just like shells can be affected by environmental factors. And since Traveller doesn't have shields, armor is the only defense. That actually makes Traveller more like WW1 gun combat, where a ships defenses comprised being seen, agility, and armor to withstand hits and near misses.
Modern warfare and obsolesence
I will clarify the modern warfare with missiles statement - a modern NAVAL war with missiles. Since WW2 there have only been a handful of incidents where missiles were used in naval combat. And certainly no one has fought a full-scale war that way. The Falklands War had a few skirmishes between the two sides. Ukraine and Russia have done the same with each other - just a few attacks and no actual engagements between surface combatants, just one side firing and the other side defending. The USN hasn't sunk a major surface combatant via missile fire except in target practice. And while they have shot down the odd individual fighter (or airliner) with missiles, those were anti-aircraft missiles and the issue being discussed here is naval (or space) ship combat. The fact of the matter is there is just not that many examples of ships being sunk via missiles. Going all the way back to WW2 it looks like there have only been 71 confirmed sinkings of ships with missiles (including the Moskva). And only 2 warships (Sheffield and Moskva) that weren't patrol boats or sunk as targets. We have very sparse data to draw upon. Russia and China do tend to invest more in offensive systems rather than defensive (when it comes to missiles) is a true statement. But it's also a reflection of (a) their desire to be more offensive rather than defensive, and (b) a reflection that Western powers tend to value the lives of their soldiers and sailors more than the East. The recent introduction of hypersonic missiles is changing the nature of the battlefield. And, as is typical, the offensive systems typically emerge first until they are better understood, and then defensive systems are developed to counter them. Again, that's been true since pretty much the start of warfare. To your point about wounds being survived in combat, that's easily explained away by (a) weapons such as the M-16 being designed to maim rather than kill since that takes more troops out of a battle (b) troops wearing body armor, and (c) advances in medical tech and the deployment of medical personnel during combat rather than after the battle. Western nations put a great deal of emphasis on trying to immediately provide assistance to wounded soldiers. I'm not sure what survival rates has to do with technical obsolescence. A gladius can still kill as easily as a musket or a round from a M2 - however the chances of a legion of Romans armed with javelins and gladius being able to destroy a modern company of infantry are extremely low. You argued that in the future missiles would be rendered "illogical" by changes in weapons, but as we have seen, as weaponry changes with tech, offensive and defensive methods also change. Arrows were replaced by bullets, rounds from a trebuchet replaced by rounds from cannons. Missiles have no real equivalent unless you want to compare them to ancient Chinese rockets. Early German cruise missiles, such as the V1 had defenses enacted once they were better understood - the V2 did not since no tech at the time was capable of intercepting it.
Targeting and targeting locks
I had said previously a laser isn't very useful unless it can it its target. To do so requires a target lock. To obtain a target lock requires either active and/or passive target acquisition AND keeping the lock long enough for your defensive fire to hit an incoming missile. For the most part I don't think a ship will have a problem 'seeing' an inbound missile. However to hit it you need a lock (unless you can fill all possible spaces at range with fire). The further distance the missile is, the higher the chances of a miss. For objects that are actively making it hard to hit them, the chances become lower. The more things (or beams) you can throw at it, the higher your chances of hitting it. At this point the other factors come into play, such as ECM (is what you are 'seeing' with your active sensors really there or an electronic forgery?), decoys and the like. Passive sensors might tell you something is there, but they aren't always the best for target locks. Since active sensors are electronic they can be fooled, jammed or otherwise rendered useless to make a positive lock on your target - without which hitting something trying not to be destroyed becomes more problematic. It's not that it CAN'T be done - but there's not a lot of point of throwing expensive things at an enemy that are easy to hit and destroy. It's only reasonable to expect your enemy is going to make it as hard as they can to get a lock and be able to shoot their missile down. Attackers may decide to throw more missiles that are cheaper rather than fewer that are expensive. That affects the types of defenses a missile might carry. It, too, can carry passive (RAM materials, ablation shielding, chaff, flares,etc) or active (electronic jammers or decoys). Adding all these things together means that there are still chances of NOT getting a good enough lock to shoot down a missile before it impact. To what extent that chance is the crux of the issue. So long as there is a somewhat reasonable chance then I think it's reasonable to expect sides are still going to use them. And at what point a side determines the credits could be better spent elsewhere is situational at best. You mentioned anti-radiation missiles as a reason AGAINST ECM - but that makes no sense. Yes, anti-radiation missiles DO exist today, but at no point has that stopped anyone from building and deploying ECM/ECCM systems. If you'll take a look at aircraft jammers and naval ships you'll see that they still build and operate them (and devious designers have built into them the ability for a ARM to even loiter as long as possible looking for targets that cycle on/off to defeat them - or even go to the last known location of the emitter. Still, nobody has stopped funding ECM).
Ablation and Nukes in space
Yes, ablation exist (reflec armor in the game, and a hull option. It's generally good to ward off the first shot. Depending on a number of factors, the level of ablation would mean it could resist X number of shots at X power - the more powerful the energy beam the less likely it's able to do it's job. A partial hit on a missile would typically render it useless, so even a partial hit should destroy or eliminate it as a target. Without factoring in the wattage of a typical point defense energy weapon one can't determine how much ablation is required, nor what the actual cost of adding ablation. Would it be cost effective? Can you economically add RAM to the surface than a layer of ablation to a missile and keep it within your cost model? I dunno - nobody else does either. But its possible, and adds to the column of whether or not missiles might still be effective in space combat. Thus it rates mentioning. You are correct that a nuclear detonation in space is much different than one in an atmosphere, and the normal worries of heat and over-pressure are lower and non-existent respectively. I had already assumed such. Getting a direct hit with a nuclear detonation would be a wonderful thing, but against a well-defended target, not necessarily a probable thing. Which is why I'd think most nukes would not be contact nukes but rather lasing nukes. For the record I don't believe I ever said a nuclear missile required direct impact, or even proximity (proximity would be a relative term - a nuclear detonation 10m from the hull would still have effect, and to what extend depends on the warhead size and the armor factor of the ship). Anti-ship attacks can be both proximity and direct contact, and depending on warhead strength and distance the impact may be significant or none at all. But I've not addressed that in my argument for the effectiveness of missiles in general. I dunno what you mean by ships at 'cosmic' speeds. Relative velocities aren't germane unless you are supposing a ship is traveling faster than the detonation (or else the velocity differential is large enough that the blast is only slightly faster than the detonation wave or fragments). I never tried to bring that into the argument since it's relative (especially if the detonation is in front of the ship then you'd have to add to the F part of the detonation equation the velocity of the ship as well... too complicated of an argument to make here). Also, I never cited Genie-2 or any other type of warhead. It would be quite simple for a missile to turn on gyros or thrusters - no need to worry about trying to match courses - and aim itself at the target, detonate and inject some of the blast strength into lasing rods and hit the ship with x-ray energy (the US had Project Excalibur to investigate this, and it's a not-uncommon theme in sci-fi warfare). No need for blast radius or over-pressure and you still get radiation damaged via the X-ray (and possibly other radiation effect, depending on distance and warhead strength).
Missile warfare costs
As mentioned above, costs of losing in a war is the highest cost you can pay. A ship is expensive. Weapons are expensive. Space warfare is expensive. But as we have seen on Earth expenses to equip a military ARE bearable. The question comes down to how much a polity is willing to spend. And equipping a first-rate military IS quite possible. The US spends more than what, the next 20-25 nations combined, and we aren't even fighting a war. We spend a ton on expensive weapons and ammunition. We plan missile swarms to defeat missile swarms. But we've only theoretically used them to determine if we need more or less. A flight2 Tico cruiser has space for 120+ missiles (and anti-ballastic SM-3 round costs like $11m EACH, and we have them on many US cruisers and destroyers). I can't debate whether or not a 52nd century navy WOULD - but I can point out that a 21st century nave DOES. Missile combat for non-military forces is, as you stated, economically non-viable from a swarm perspective. Pirates don't have that kind of money and merchants don't want to spend that kind of money. Energy weapons are much more economical.
Fin
I've tried to refute your points with what has happened historically. Neither of us can fully predict what will or won't occur 30 centuries from now. All we can do is draw upon history and historical precedents. Humanity in Traveller appears to be no different than humanity today - still warring, still rich, still poor, still fighting over resources and beliefs. It's not Star Trek (but even they have missiles/torpedoes and energy weapons and they still are effective in combat). So long as there is a need for war there will be the need and desire to project power. A ship allows a planet to project power, a missile allows a ship to project power. As we've seen throughout history weapons will come, defenses will be established and new weapons will come on top of those. Infantry are still trained in personal combat, people still get killed with knives. I'm not speaking from a personal view. I'm citing history and reality. My entire point has been that like you, others have said this invention or that has rendered something older obsolete (you used the term illogical). But historically that's not the case. Things have changed as tech has changed (fists to rocks, arrows to bullets, bigger rocks to missiles). But conceptually we still throw things at people trying to hurt them before they hurt us.
I think missiles, in whatever future format they will morph in to, will remain a factor in warfare (in space.... cue announcer echo).
Ships being sunk by missiles - I can't do much about time scales and examples. Aside from tests we simply have no other examples to draw upon since there haven't been any other examples to draw upon. The fact that Argentinians imported French aircraft and missiles to sink English frigates can't be helped (nor can the irony). Exocets were deadly then, and are deadly today with all their upgrades. Further details are still needed for the sinking of the Moskva, but the fact that a pair of missiles sunk a cruiser that had been refitted with up to date Russian ECM/ECCM, countermeasures and CIWS systems stands on it's own. The question about the state of the systems at the time of the attack would be no different for ships in the 52nd century. Since its an equivalency across the centuries, it's a moot point. The Neptune is essentially a reverse-engineered KH-35 missile. The KH-35 is about 20yrs old. Neptunes are only a few years old and only recently entered service. The issue of a ship moving in only 2 dimensions is point, but not especially valid. The Neptune is a sea-skimming missile that moves essentially in the same dimensions (i.e it's not making large or rapid changes in it's altitude). If we translated this to space then both target and missile would be able to maneuver in 3-D, so again it's a matter of equivalency. Velocities of the target and the missile could be factors - but you'd have to provide relative speeds AND maneuverability of each in order to argue pro's or con's. A fast moving large target that is not agile is still a fast moving target. Whichever of the two has the greater ability to change course/heading is going to win the dodging game.
Costs for attackers/defenders This is an interesting argument. At the highest level, losing is the ultimate cost. Then comes how much each side is investing in their own defense, and after that what their relative costs are. For the sake of comparison we'll have to assume all relative costs of production and procurement are equal. And that all sides are willing and able to spend for their own defense. That just leaves how many credits an attacker would need to expend to take out a defender. We already know from our own reality that nations are willing to expend on their defense. To what extend depends upon the nations' capabilities. The US was willing to spend heavily to protect a carrier battle group. Aegis radars cost $1 billion dollars per platform (at the time of their launch). A single Phoenix AAM cost abou $500k and a Tomcat carried 6 of them. Then there was the cost of an SM-2 missile - a Tico-class cruiser carried almost 70 of them. The frigates and destroyers in the battle group carried more. The Soviets desire was to overwhelm the defenses through air, surface and sub-surface launched missiles. The cost of a missile capable of being launched at a distance (so your launching platforms have a fair chance of survival) is going to be roughly the cost of the counter-missile. It's not really practical to compare Soviet and US costs for a variety of reasons. The cost of a missile swarm (and protecting against it) is inconsequential because both the USN and Soviet sides DID actually spend the money to create the capabilities to do so AND to protect against it. To date, however, it's only theoretical since we didn't go to war. As you correctly point out, they were [GAMED] by both sides. And, as facts point out, both sides expended vast sums because they felt that it was needed in order to accomplish the mission - that of eliminating (or protecting) your carrier battle groups. The only thing that would remain debatable is which side may have come out of the simulated combat and still be able to perform their mission. No nation has ever performed this except in simulations. And since both sides have continued to invest heavily in newer and more modern systems, I would say that each side still believes it is possible (however improbable).
Transition away from big-gun ships to aircraft and missiles I think you missed the point about the transition away from guns to aircraft and missiles as the primary way for naval craft to fight with one another. Carrier borne aircraft DID put an end to the era of big guns, as evidenced by the combat that took place during WW2. There were very few instances of surface fleets engaging each other with only shipboard guns. Pretty much every fleet action in WW2 was with aircraft and not guns - though there are some interesting and notable exceptions. Once aircraft proved that they were able to project power and sink surface vessels, they became the primary ways to project power at sea. And yes, they did so through guns, bombs and torpedoes. I don't know what point you are trying to make mentioning curvature, gravity and the inability to shoot through the planet. Both ballistic and direct-fire trajectories accomplish the same thing - delivering your payload to the target. Whether it's done 2D or 3D is irrelevant. The only things that matter is that your offensive projection ability exceeds the targets defensive capabilities and you are able to cause damage to your target. To what extent you feel the need to "drive home" curvature is something that you will have to explain further. I don't see the relevancy. The point of any attack (gun, beam or missile) is to affect the target - exactly HOW it gets there doesn't really matter. Laser weaponry can be affected by sand, by anti-laser aerosol, etc, just like shells can be affected by environmental factors. And since Traveller doesn't have shields, armor is the only defense. That actually makes Traveller more like WW1 gun combat, where a ships defenses comprised being seen, agility, and armor to withstand hits and near misses.
Modern warfare and obsolesence
I will clarify the modern warfare with missiles statement - a modern NAVAL war with missiles. Since WW2 there have only been a handful of incidents where missiles were used in naval combat. And certainly no one has fought a full-scale war that way. The Falklands War had a few skirmishes between the two sides. Ukraine and Russia have done the same with each other - just a few attacks and no actual engagements between surface combatants, just one side firing and the other side defending. The USN hasn't sunk a major surface combatant via missile fire except in target practice. And while they have shot down the odd individual fighter (or airliner) with missiles, those were anti-aircraft missiles and the issue being discussed here is naval (or space) ship combat. The fact of the matter is there is just not that many examples of ships being sunk via missiles. Going all the way back to WW2 it looks like there have only been 71 confirmed sinkings of ships with missiles (including the Moskva). And only 2 warships (Sheffield and Moskva) that weren't patrol boats or sunk as targets. We have very sparse data to draw upon. Russia and China do tend to invest more in offensive systems rather than defensive (when it comes to missiles) is a true statement. But it's also a reflection of (a) their desire to be more offensive rather than defensive, and (b) a reflection that Western powers tend to value the lives of their soldiers and sailors more than the East. The recent introduction of hypersonic missiles is changing the nature of the battlefield. And, as is typical, the offensive systems typically emerge first until they are better understood, and then defensive systems are developed to counter them. Again, that's been true since pretty much the start of warfare. To your point about wounds being survived in combat, that's easily explained away by (a) weapons such as the M-16 being designed to maim rather than kill since that takes more troops out of a battle (b) troops wearing body armor, and (c) advances in medical tech and the deployment of medical personnel during combat rather than after the battle. Western nations put a great deal of emphasis on trying to immediately provide assistance to wounded soldiers. I'm not sure what survival rates has to do with technical obsolescence. A gladius can still kill as easily as a musket or a round from a M2 - however the chances of a legion of Romans armed with javelins and gladius being able to destroy a modern company of infantry are extremely low. You argued that in the future missiles would be rendered "illogical" by changes in weapons, but as we have seen, as weaponry changes with tech, offensive and defensive methods also change. Arrows were replaced by bullets, rounds from a trebuchet replaced by rounds from cannons. Missiles have no real equivalent unless you want to compare them to ancient Chinese rockets. Early German cruise missiles, such as the V1 had defenses enacted once they were better understood - the V2 did not since no tech at the time was capable of intercepting it.
Targeting and targeting locks
I had said previously a laser isn't very useful unless it can it its target. To do so requires a target lock. To obtain a target lock requires either active and/or passive target acquisition AND keeping the lock long enough for your defensive fire to hit an incoming missile. For the most part I don't think a ship will have a problem 'seeing' an inbound missile. However to hit it you need a lock (unless you can fill all possible spaces at range with fire). The further distance the missile is, the higher the chances of a miss. For objects that are actively making it hard to hit them, the chances become lower. The more things (or beams) you can throw at it, the higher your chances of hitting it. At this point the other factors come into play, such as ECM (is what you are 'seeing' with your active sensors really there or an electronic forgery?), decoys and the like. Passive sensors might tell you something is there, but they aren't always the best for target locks. Since active sensors are electronic they can be fooled, jammed or otherwise rendered useless to make a positive lock on your target - without which hitting something trying not to be destroyed becomes more problematic. It's not that it CAN'T be done - but there's not a lot of point of throwing expensive things at an enemy that are easy to hit and destroy. It's only reasonable to expect your enemy is going to make it as hard as they can to get a lock and be able to shoot their missile down. Attackers may decide to throw more missiles that are cheaper rather than fewer that are expensive. That affects the types of defenses a missile might carry. It, too, can carry passive (RAM materials, ablation shielding, chaff, flares,etc) or active (electronic jammers or decoys). Adding all these things together means that there are still chances of NOT getting a good enough lock to shoot down a missile before it impact. To what extent that chance is the crux of the issue. So long as there is a somewhat reasonable chance then I think it's reasonable to expect sides are still going to use them. And at what point a side determines the credits could be better spent elsewhere is situational at best. You mentioned anti-radiation missiles as a reason AGAINST ECM - but that makes no sense. Yes, anti-radiation missiles DO exist today, but at no point has that stopped anyone from building and deploying ECM/ECCM systems. If you'll take a look at aircraft jammers and naval ships you'll see that they still build and operate them (and devious designers have built into them the ability for a ARM to even loiter as long as possible looking for targets that cycle on/off to defeat them - or even go to the last known location of the emitter. Still, nobody has stopped funding ECM).
Ablation and Nukes in space
Yes, ablation exist (reflec armor in the game, and a hull option. It's generally good to ward off the first shot. Depending on a number of factors, the level of ablation would mean it could resist X number of shots at X power - the more powerful the energy beam the less likely it's able to do it's job. A partial hit on a missile would typically render it useless, so even a partial hit should destroy or eliminate it as a target. Without factoring in the wattage of a typical point defense energy weapon one can't determine how much ablation is required, nor what the actual cost of adding ablation. Would it be cost effective? Can you economically add RAM to the surface than a layer of ablation to a missile and keep it within your cost model? I dunno - nobody else does either. But its possible, and adds to the column of whether or not missiles might still be effective in space combat. Thus it rates mentioning. You are correct that a nuclear detonation in space is much different than one in an atmosphere, and the normal worries of heat and over-pressure are lower and non-existent respectively. I had already assumed such. Getting a direct hit with a nuclear detonation would be a wonderful thing, but against a well-defended target, not necessarily a probable thing. Which is why I'd think most nukes would not be contact nukes but rather lasing nukes. For the record I don't believe I ever said a nuclear missile required direct impact, or even proximity (proximity would be a relative term - a nuclear detonation 10m from the hull would still have effect, and to what extend depends on the warhead size and the armor factor of the ship). Anti-ship attacks can be both proximity and direct contact, and depending on warhead strength and distance the impact may be significant or none at all. But I've not addressed that in my argument for the effectiveness of missiles in general. I dunno what you mean by ships at 'cosmic' speeds. Relative velocities aren't germane unless you are supposing a ship is traveling faster than the detonation (or else the velocity differential is large enough that the blast is only slightly faster than the detonation wave or fragments). I never tried to bring that into the argument since it's relative (especially if the detonation is in front of the ship then you'd have to add to the F part of the detonation equation the velocity of the ship as well... too complicated of an argument to make here). Also, I never cited Genie-2 or any other type of warhead. It would be quite simple for a missile to turn on gyros or thrusters - no need to worry about trying to match courses - and aim itself at the target, detonate and inject some of the blast strength into lasing rods and hit the ship with x-ray energy (the US had Project Excalibur to investigate this, and it's a not-uncommon theme in sci-fi warfare). No need for blast radius or over-pressure and you still get radiation damaged via the X-ray (and possibly other radiation effect, depending on distance and warhead strength).
Missile warfare costs
As mentioned above, costs of losing in a war is the highest cost you can pay. A ship is expensive. Weapons are expensive. Space warfare is expensive. But as we have seen on Earth expenses to equip a military ARE bearable. The question comes down to how much a polity is willing to spend. And equipping a first-rate military IS quite possible. The US spends more than what, the next 20-25 nations combined, and we aren't even fighting a war. We spend a ton on expensive weapons and ammunition. We plan missile swarms to defeat missile swarms. But we've only theoretically used them to determine if we need more or less. A flight2 Tico cruiser has space for 120+ missiles (and anti-ballastic SM-3 round costs like $11m EACH, and we have them on many US cruisers and destroyers). I can't debate whether or not a 52nd century navy WOULD - but I can point out that a 21st century nave DOES. Missile combat for non-military forces is, as you stated, economically non-viable from a swarm perspective. Pirates don't have that kind of money and merchants don't want to spend that kind of money. Energy weapons are much more economical.
Fin
I've tried to refute your points with what has happened historically. Neither of us can fully predict what will or won't occur 30 centuries from now. All we can do is draw upon history and historical precedents. Humanity in Traveller appears to be no different than humanity today - still warring, still rich, still poor, still fighting over resources and beliefs. It's not Star Trek (but even they have missiles/torpedoes and energy weapons and they still are effective in combat). So long as there is a need for war there will be the need and desire to project power. A ship allows a planet to project power, a missile allows a ship to project power. As we've seen throughout history weapons will come, defenses will be established and new weapons will come on top of those. Infantry are still trained in personal combat, people still get killed with knives. I'm not speaking from a personal view. I'm citing history and reality. My entire point has been that like you, others have said this invention or that has rendered something older obsolete (you used the term illogical). But historically that's not the case. Things have changed as tech has changed (fists to rocks, arrows to bullets, bigger rocks to missiles). But conceptually we still throw things at people trying to hurt them before they hurt us.
I think missiles, in whatever future format they will morph in to, will remain a factor in warfare (in space.... cue announcer echo).
