Is it intentional that the frost orb things that explode aren't able to be hit by gun bullets? I doubt this is intentional... doesn't make it difficult, but it is just plain annoying if anything.
If a gunner is to use auto attack, then the frost orbs will be targeted then shot at but nothing will happen. Not that gunners really should be using auto attack so they can shoot inbetween enemies, but either the developers need to A. Make auto target not target the frost orbs, or B. Make the frost orbs able to be hit by bullets so that things are fair.
This is a place where bombers shine. I mowed those stupid orbs down without trying, as long as I was bombing something else. AoE for the win!
Given that you were saying we don't need a ranged bomb to make it fair, since it's not about being fair but about having balanced load outs, I think it's fine that gunners can't hit the orbs well. Makes them use bombs. Then they can feel all the hate we get.