I am against this. Yes, the AC buff has negatively affected stuff like fireball (or shatter in EA) which purely focus on damage, but casters are most powerfull when they play controllers.
Just because enemies have 15% more health, or whatever the number is, should not mean, that it is easier to hit your hold monster, disintegrate or banishment. That is FAR more potent than dealing a few hit points more, especially against bosses
