I took it not as the tentacles being evil but as that they had only one purpose: FUSION! Until the filter blew, Doc Ock provided the moral guidance, but after that they just did whatever it took to get money/deuterium/whatever.

Peter's power failures seemed to be a "use 'em or lose 'em" sort of thing; once he stopped using his powers and stopped being motivated to have them, he started losing them.

Obviously, I have a highly-developed rationalization gland from years of reading comics and watching SF movies.