Enrage timers are necessary at this point, at least until they work out mechanics and figure out how to design interesting encounters. Right now, a fight is two or three gimmicks and an enrage. Not very complex, but they were probably rushed out to meet EA's release date. That said, none of them are particularly bad for what they are. Eventually everyone will outgear them and not have any reason to go back anyway. If we're still seeing 5 or 6 minute zergfest bosses populating raids in the future, then it's time to start worrying.