Valid point there, but I think it works the other way around.
It seems that Bendis' work on Ultimate Spider-Man and Ultimate Six leans towards saying that bad guys will always be bad guys. I distinctly remember Peter and Fury being very explicit about this.
I lent out my hardcovers, but the gist of what Peter said was that Norman Osborn was an evil, crazy, s.o.b. way before he jumped himself up on Goblin juice. And in Ultimate Six, Fury states that "Greedy and crazy are always looking for ways to be greedy and crazy." Which means that the only difference between the Osborn, Kravinoff and Octavius and their superpowered personas is that power gives them the ability to act on their own corrupt natures.
People like Xavier and Parker aren't benevolent and kind IN SPITE of their power. Instead, they were good people before they discovered their own power, and when they got their powers they were psychologically stable enough not to go on some kind of mad power trip or delusional thoughts of self-entitlement. Osbron, et al. were already sick bastards BEFORE they got their powers and power did nothing to change that or put that into action.
Which is why Fury hangs his head low when Captain America tells him that it's people like Fury who "will the war into existence" and determine what those wars will be about. He knows very well what having all that power means, and trying to live up to the enormous responsibility that entails is a struggle for him: A struggle to not be corrupted by that power.