Be careful confusing "has no opinion" with "moron". The voir dire process tries to select for people who have no opinion: it's specifically designed to filter for neutrality, because if the trial hasn't even begun yet and you have an opinion, that's a problem.

There are some people - oftentimes very literate people - that mistake having no opinion for being stupid. It's very far from that. Oftentimes being neutral and keeping your mouth shut is the smartest thing you can do. There's frequently a popular image of someone who is smart as someone who is very quick to form judgments and articulate them with little information; this can be a useful skill in certain situations but is the opposite of what our legal system wants in a juror.