I've been playing DCUO, and yes, the who Exobyte-Nanotech-Whatzit explination is indeed lamesauce. Also lame, the limited costume editor and "archetype" selections. I like the way it handles super-speed and the way the flight animations are handled, but aside from that I prefer the CoX game-play.
Granted, I have made a semi-decent version of Avatar of RA over there that I like playing, but it doesn't draw me in like CoH, and I enjoy it in spite of the back-story, not because of it. Its cool to "rub elbows" with the likes of Superman, Wonder-Woman, Batman, etc, but its a novelty that eventually wears off.