I didn't read Idiocracy as eugenics/anti-eugenics. It wasn't saying that stupid people breeding made the population stupid, it was saying that the less educated breeding resulted in the more educated being pushed to the periphery and eventually fading out.

The people of the film's future were not stupid, just massively uninformed and misinformed. They were able to grasp the problem and solution in the end.

Unless I'm misremembering, and it did make direct reference to intelligence rather than education and access to it. It is a good few years since I last watched it. There is the title, of course, but educationally-disasavantaged-ocracy would not have been catchy enough!