I would see Riker's understanding about everyone not wanting their gifts and restoring things to what they were to be responsible. I still don't see how that means he should flat out reject his power. When you learn to use something in a responsible manner, why throw it away?
I would have liked to have seen this episode actually delve into that discussion on how someone would want to use these powers in a responsible way. But instead of getting that, we have our main heroes resorting to opinion based absolutes to say it's wrong.
Well to be fair, this wasn't any old power, but the "Power of the Q." It's possible Picard felt there was something much more corrupting and insidious about it's use-- and considering Q's behavior towards them, I'd say that's probably a safe assumption.
And indeed, Riker does very quickly start to develop a massive, Q-sized ego.