Blah, none of you want to call it mitigation instead of resists.
Even though a lot of AEs now use 0-9, 9-14, 14+ damage scaling... mitigation is still a factor after that. Especially for power drains. It's just that if you're standing at 15m, you don't really care past what your standard gear gives you for that mitigation type.
Range damage scaling is both interesting, and dumb at the same time. They wanted a way to make AEs avoidable, and yet not 100% avoidable for the debuff effects. It's just unfortunate that they made mitigation not worthwhile to most people except tanks or melee that don't get out of harm's way.