Firing arcs do not make sense unless you have a full 3D battle environment ... and a way to tell the AI how to handle that, what most likely is out of the scope of any game. If you go with a plane, or ship-stacking like SE5, or even "limited 3D" like Imperium Galactica II (with AI absolutly unable to use it), you're doing so many assumptions about how ships move and turn, that the assumption that they could -briefly- pointed anywhere to fire at a random target seems rather minor. Remember: In space, you don't go where your bow points, but where inertia carries you (Hollywood never gets that right, they always show WW2 fighter combat ...), and turning a ship on its C.G. would require very little engine power in comparison to what you need to e.g. get out of a planets gravity well.
Placements of components should have a much bigger impact, or actually, the
function of the component should have a much bigger effect on where it must be placed. (In fact, I think, SE3-5 got it almost -wrong- every time

) E.g. it should be mandatory that sensors are mounted
outside even the armor, unless they're fantastitech hyperspace sensors. And sublight engines must have some kind of unarmored exhaust, unless, again, you have reached inertialless gravity drives, or something. And, o.c., while armour should be a fine thing to have, it's pretty obvious that there shouldn't be a need to desintegrate every tiny bit of armor before a ship goes BOOOM ... critical hits to internals through holes shot in the armour beforehand should do that much earlier. (IIRC , SE3 got that mostly right).
What else would I like to see in space battles?
- Drifting hulks of ships that lost power (reactor), which are out of the fight, but could be salvaged by the winner. Ships breaking apart long before all their armour and internal components have been destroyed (decouple structural integrity points from components!).
- Really long-ranged long range weapons (E.g., missiles in stock SE5 are laughable: a fighter has to get there, fight, and get back, and does so over the whole battle map, while CSM barly cover the diameter of a big planet...)
- leaky and unleaky shields
- ability to retreat for both sides