cost is the deciding factor
there is no reason to switch from 6061 when it fits perfectly in most paintball applications
now if there were an actual strength requirement where you would be better off using 7075 that would be a design exception
from a business perspective it simply makes no sense to use a more expensive material when you end up with an identical part for a significant decrease in cost of the material
if you are comparing it to 7075, yes it is softer, but to say you have to start affecting speeds and feeds for every tool, I totally disagree
I have extensive experience machining both and I use identical speeds and feeds for both, and they both machine beautifully (7075 more-so because it does indeed break chips a little better due to the decrease in ductility)