I don't see how it's remotely over powered. In PvE it might be a helpful tool for inexperienced progression groups but it will never be used in a serious score pushing run and it won't help with no death achievements, which are typically tied to the most desired titles and rewards in PvE content. In PvP it might be more useful but it still requires you to hold an ultimate until your allies are dead instead of using another ult to prevent them from dying in the first place. Using the rez ult will essentially just be playing to lose in most situations.