Nope. That would not be required. First of all... facing is already a part of the game when you ask PCs to specify where they are or they use a mini to show you where they are. Or do you not let your PCs sneak up on someone 'from behind'?
Stealth and facing rules arent the same thing.
Facing rules is strictly a combat mechanic, which matter more for mini war games, then it does for ttrpg. Facing for war games determine what they can aim at, which vector they're being aimed at from. And for person to person combat, this edition, doesnt care about it.
This can become a hydra problem. They go into combat with an open jacket. Is it a free action to close it. Is it a simple action. Is it a complex action. Are you going to go through the start of every combat to ask them how they're dressed and how its sitting on them before each combat?
How are you going to track this for NPCs? Are you going to do little dottles to mark where the armor is open on them, or how it cover them. Are you gonna do a dottle of every combatant, with a front, back, side, side of how much each armor is covering.
If the player state where they're aiming and if ther an open slot, how do you determine if it the 2/3 of the chest is cover by the jacket verses the 1/3 that isnt. Or if the jacket is open, are you treating it as if the jack front flaps just go into a pocket dimension when open and the front of the chest is exposed?
What is this really solving?
I appreciate your input from your experience. Thanks. I guess in my way of thinking a one-shot kill should always be possible especially where no armor is being used. That's more like our reality where people can actually be killed with a single punch even. I do like the 'Effect' system Traveller uses adding damage based on 'Effect', and maybe that's the key to getting those one-shot kills. A skilled fighter with a dagger and +4 to hit can do some better damage (1D+2+4).
For this system, even though it doesnt have called shot for melee combat, you can declare to do something harder, like aim for the neck or aim for the heart or other organs.
For my table, I would probably declare that their END is reduce to zero and that your damage roll is applied a second stat.
Mechanically, this edition, doesnt have a bleed out during combat mechanic. You can die after combat, when natural healing starts to happen.
You can also describe something like this happening if the attacker rolled and MoS +6 which is kinda, sorta a critical hit.
Respecting the narrative circumstances is fine.
I'd do the same if someone aimed for the head in particular with a gun for similar results or more, depending on narrative circumstances.
Pretty sure most Traveller Refs let enemies shoot at their PCs with firearms. I don't think character generation is relevant to the problem I'm seeing.
Frequent combat means having frequent new characters. Which is fine if everyone knows that going in.
Looking online, I found reference to one Ref who simply ruled that energy weapons ignored all armor. Not something I would do, but it does suggest to me that I'm not alone in seeing an issue.
One idea I am playing with is simply increasing 'effect' damage. Instead of 1 point of extra damage per 1 point of effect... I wonder what doubling that might do. So effect of 4 would mean +8 damage. I like this idea because it ties additional damage to the roll... basically just increasing the result of a more 'critical' hit.
I wouldnt really worry about lasers.
While lasers were shit canned in this edition, they arent worthless. They're more niche. They're zero gee, have basically infinite ammo, invisible to see. They have more narrative options than guns.
For my table, I give all laser guns free laser dot.
And investing in gun combat energy, lets you use the stun weapons, which are amazing.