There'd have to be another angle to it. It could not be pure aggro, as pretty much everyone else has mentioned that'd be extremely boring even if it was harder to do somehow, because the game wouldn't reward you as it does a good tank now (faster fight clears/DPS checks met easier/allowing you to meet enrages undergeared). There'd have to be some survival edge to even consider something like that, something like all your aggro has permanent Bloodbath attached to it, or your debuffs on the enemy are based on stats or something ... I don't know, hard to see how it would work, or why a dev would even go that route when everyone's DPS crazy these days.

It'd also complicate solo play tremendously.