Well, for GC if they have Z95 they might be more useful than Xwings due to their low cost.
The only thing I can see Fighters being useful is for air contrl, since in GC computers can build ships without a space station as long as their orbit is clear.
That having said you can do the same with a unit of Ys, and Ys are better cause they give Orbital when your ground force arrives.
In skirmish Xwings are useful, cause with X-foils locked they last for a long time, perfect for spying and resources grabbing.
But Yes, bang for bucks any corvettes are going to be better than any fighters. Don't get me started on the elight fighters, they are even worse. Anyone see any real use of Awings? Unless you count "lure stupid computers to shoot them instead" as a function, then yeah they are almost useful, but other than that its just as useless as the Imp elite. For the Imps, Map revealing ability is great on ground battles (ground battles you can instant orbital generators ftw), but in space it accounts for much less.
Generally speaking, to make fighters useful, they have to cost less pop-cap. I think if they are like 2-3 units for each ONE pop-cap like ground Inf they might be better. Raise the price accordingly if you want, but at least then they provide more firepower for the battle.