I think there's some merit to this idea, but instead of one power set we'd need, we need 8.
One of each for the following: Armor, Assault, Blast, Control, Manipulation, Melee, Pets, Support....plus I guess blend them as needed to get the EATs and VEATs sets.
Each set should have a variety of ridiculous effects with some crossover in themes but maybe something different about each one. And for a one day only special event, when everyone logs in, all ATs have their power sets replaced by the appropriate type. Slotting doesn't change, just what happens when you use the powers you thought you had. I think April might be a good month to have this event, but after the first day it could get really irritating and so should end pretty quickly.