To be fair, there's no indication that Roddenberry "thought that human nature could be re-shaped to suit a politico-economic ideology". It seems to me that he thought that technology would remove the impetus in humans to those impulses - that it would re-shape itself of its own accord.
And I mean - I dunno. People talk about 'human nature' but there used to be slaves fighting to the death in ancient Rome. People used to tie cats to sticks and burn them in public for entertainment only a few hundred years ago (by which time gladiator-slaves weren't seen as acceptable). Sensibilities do change.