Faction line SNACs were proposed a while ago (can't remember thread, not going to look) but were not included for one reason or another. They varied the SNAC damage, energy usage, refire to varying degrees for different factions. The argument against it was that everyone would just go for the one that did 10k damage more per shot, but took one second more to refire. One-size-fits-all remained.
Faster, less powerful bomber guns? You mean like the fighter guns that were so recently taken off Bombers? They say that if you don't learn from history, you're doomed to repeat it. Hmm...
Bomber EMP. Outcasts would probably be the first to make it really, ramping up their Infernos. Problem then becomes the public outcry for fairness in that all factions should have that opportunity. It would also make bombers like the Mjolnir, Barghest, and Challenger uber-powerful, and lighter bombers would be left with a difficult choice to make that will put them at a disadvantage. [insert "fly with wingmen" argument here]
Bomber mines. Sounds like fun, but what would the explosive radius be? Also, even with a slow (40m/s) travel speed and massive damage, they better hit an unshielded ship, or they're a waste of resources.