Most of the Megas do look just ridiculously overpowered. But you only get 1 per team. Meanwhile every consistent, high BP move got nerfed, we got new protects, and a few new crazily defensive mons. I'll agree that the MEvos are a push in the offensive direction, but its going to be a limited push because we're limited to one per team. The other 5/6ths of your team is still the same old same old, using weaker, less consistent attacks and dealing with new defenses.
I'd just like to make one correction: every consistent high BP special move got nerfed. It seems like the physical powerhouse attacks are unchanged.