It's easy to read too much into these surveys that expose scientific/math/geography illiteracy among the U.S. population. You know, the ones that show how a large percentage of students can't find the U.S. on a globe or name the current President. But there's plenty of ignorance to go around: after being pressured to join my office basketball pool, for example, I realized that I didn't have any idea how many periods they play -- something that I'm sure a lot of people would find to be an incomprehensible gap in knowledge. (Ask me about bicycle racing, MotoGP, or rally and I might have a little more to offer.)
Sure, I think it's important to understand that the earth revolves around the sun. To me, this seems like a basic fact about the world that everyone ought to know. But I can also accept the idea that not everyone views this as relevant information. In particular the sun thing. After all, personal experience and language itself tell us that the sun "rises" in the east and "sets" in the west. And it doesn't really hamper your day-to-day life to believe otherwise.
When it comes to believing things that aren't true, I'd much rather see a reduction in the number of people who believe in miracles, new-age "medicine", psychics, and so on -- beliefs that, if acted upon, could actually harm you or your children.