The main issue that troubles me in this is that you are saying very clearly that bombers didnt destroy capships before FS1 era.
I think that's pretty likely to be the case. There's certainly very little evidence that a bomber wing on its own ever destroyed a capship. It's like saying that bombers sunk the Bismark. They didn't they put it out of commission, yes but the Bismark only sank cause the crew skuttled it.
And you seem to leave no possibilities for pure small craft assaults (bombers and their escort fighters) being able to destroy any capships in pre-FS1 era.
I don't doubt that they killed cruisers now and again. Maybe even quite often. They may have killed capships at the start of the war too but I simply don't see it as very likely that any bomber could take out an Orion.
Even though we know practically nothing about the pre-FS1 era equipment, weapons, bombers, or fighters. Im not sure if you meant it in that way but it sounds awfully lot like it.
I'm not stating it as fact but I am saying that it fits the evidence better than having bombers able to kill capships. If bombers could kill caps why was the Taranis seen as a threat? Couple of wings of vasudan bombers could have dealt with it surely? In addition to that it also makes a nice progression. You can see why the GTA built great big destroyers in the first place (only things that could kill other ships their size) instead of going down other routes. Furthermore if you have to park up next to an enemy destroyer and bombard it with your guns for such a long time to kill it, it explains why the war was such a stalemate.