How much of this power creep talk boils down to the new deadly prefix? That is pretty small, almost tiny, in comparison with what kind of power epic destinies brought. I'd give odds it's a purposeful change by Turbine in order to try and close some gaps between the weak on average melee damage output in heroic levels compared with aoe blasting sorcerers and blade barrier kiting divines. A fighter can hit for +6 damage at level 15 now? Cool, that's going to help him when there's one mob left standing from the group of six that were just incinerated by dbf.
U19's "power creep" is pretty light on the "power", pretty slow on the "creep".