There weren't, but you may be thinking of missiles with submunitions, or the odd missile armed fighters in SotFA, which can't actually control their missiles. Based on the art, submunition "bombs" are a better fit.
The Kennedy was a fusion frigate type with a couple of sensor drones and 20 missiles with semi-active control. The design philosophy was to use the drone as a spotter (37 million each), and vector long range missile strikes (8.4 million each in the design sequence, but discounted) onto a target probably using the drones active sensor as illuminator. The idea was the Kennedy should never receive return fire, hence the lack of investment in guns and defences.
It actually makes better sensor to place a small crew on the sensor drone and call it a spotter. It gives a lot more independence of action to the spotter.
Given the rules for defensive fire as written in Star Cruiser, each turret can have two bites of the cherry when defending - each can fire during the movement and fire phase, and then each can fire again during the detonation phase (assuming a same hex detonation). This means a ship of a reasonable size can slaughter missile strikes. Further, fleet tactics will have the main line stacked up in a single hex with coordinated defensive fire.
As the scale of combat goes down, missiles become a more dominant factor. They dominate in skirmishes of light forces, but are near useless at long range in large actions. See
here.
The truly (cost) effective weapon system is a well armoured submuntions armed heavy fighter. Groups of fighters stand much more chance of surviving
The nature of the target matters. Terrestrial missiles and planes are traversing a different medium than the ships, and so are much faster but also more vulnerable if hit. In 2300AD space combat all vessels, including missiles, have basically the same characterisics. The weapons used to engage ships and missiles are the same.
Herein, the physics of lasers matters. Range is directly proportional to the diameter of the focal array (or individual element a multi-array). SC lasers are 6 m in diameter, and so the high-X laser can focus to 600,000 km. A smaller laser has less range. Range = engagement time. Further, although the physics say the effective range of a det-laser is only a few 100 km at best, the SC rules as written (and Mongoose rules) treat det-laser as focused lasers and allow them to attack by stand-off detonations. Any defensive weapon that doesn't outrange the detonation distance is useless.
The general question for navies in the gun period was always the maximum number of
effective guns. In the 19th century, gun size increased with increasing armour, initially thicker wood (making 12 pdrs etc. ineffective resulting in 32 pdrs being standard), and then metal armour, resulting in smaller numbers of larger guns. The aim is to have your guns be effective against the enemy armour, and to maximise their number by not having them too large. Before predicted aim this equilibrium was found around the 12 inch gun. The later plunges into 13.5", 15" then 16" weapons was driven by increasing ranges at which hits could be achieved, and the need for those hits to be effective.
The fly-in-the-ointment was the development of an asymmetic weapon, the propelled torpedo. This meant a much smaller vessel could hit a battleship with a very powerful weapon (and remember, ca. 1880 battleships actually carried a couple of torpedo boats). The counter was a large number of effective guns against these smaller vessels. Then the small vessels started to get larger and more capable, necessitating larger guns to counter them etc. As these became too large for enough of them to be mounted on battleships, additional small ships were needed to ship them creating the destroyer.
The question here is whether smaller guns would be useful in 2k3. The x1 laser is the standard weapon, and is very multipurpose - it has good range, can penetrate most ships and can shoot down missiles. However, in the 2280's new armour materials have been developed which make ships which can't be penetrated by x1 lasers (armour-10, like the Martel or typo corrected Richelieu) viable. It may be that ships start carrying x2's or even x3 PBWS's to penetrate each others hull, and in that case a split to have a secondary battery would make sense. It just hasn't happened yet. Kafer ships have these same armour levels, and so the trend in naval architecture probably will soon generate a primary/secondary battery split...
