Probably a slightly crazy take but I actually think the loiters can stay exactly as powerful & impactful as they are right now IF all factions get an AA unit that is exactly as effective vs loiters as the USF M16 Quad.
If the opponent has one M16, the axis loiters won't even make it until their first strafe. Feel free to test yourself in cheat mod
USF doesn't have any attack loiters, you mean the rocket loiter from British Air & Sea BG
I do agree with that, but I feel like 120 munis is too little for the impact it has/can have.
On one hand, many of the maps give you boatloads of munis and on the other hand some other abilities like the emplacement killers (e.g. USF bombardment, UK shipbarrage) cost more and tend to have varying impact (either it kills just the stationary units or the enemy sleeps and loses more than that).