The combat system of GC3 was never going to be its strong suit, but it really is disappointing just how pointless most of it's potential is.
Only 3 roles matter, defenses are generally pointless, if they did matter, it's better to get jamming anyways, and carriers are poorly implemented in my opinion.
Oh and the game generally favors large ships only and has no mechanic to balance fleets or individual designs.
Perhaps things will improve when Frogboy stats looking at getting the AI to design it's own ships (he mentioned something about this recently).
Ideally, I think we may need to ditch roles and basically build those roles out as part of hull sizes. Similar to homeworld games.
Tiny = extra effective vs large and huge
Small = extra effective vs Tiny
Medium = extra effective against Small
Large and Huge = extra effective against Medium
The above isn't a perfect system or anything, it's a 30 second idea... but it actually starts encouraging somewhat balanced fleets. Which I think would be more fun.