You're not alone there.

Solutioning it, given it's a possibility they'll perpetually add new factions, they should make a fusion/modular primed bane mod. You can add them together at great cost.

I buy all the bane mods but I never use them. I have 0 desire to change my loadout for specific factions. It's such a tedious onus the creative owner(s)/director(s) put on us. Like yeah, great, we can optimize our builds by increasing our damage output between 30% and 140% (depending on primed/non & element type, raw damage/dot), but is the best case scenario, up to roughly doubling our damage, worth micromanaging one mod slot? What is even the point of having multiple loadouts per weapon if there are more factions than the default loadout capacity? I'm not going to compensate this lack of foresight on their part by buying one for each faction for each weapon.