Yeah, I agree that he is well established. Everybody knows who Superman is, what his weakness is, etc. But that doesn't mean they care. Look at some of the responses in this thread, while everybody knows who Superman is, some people think he's an outdated superhero. This reboot needs to make Superman a compelling character again. We need a Superman movie where the audience is totally sucked in and as soon as the credits roll, we want to hear about news for the sequel. Nolan did this exceptionally with the Joker card at the end of Batman Begins, but that wouldn't have worked if it wasn't a great movie that made people give a shit about Batman again.
Now, just to clarify, I don't want them rehash the same old origin story again. I would also prefer to see a villain other than Lex Luthor. But I think they need to focus on making a compelling franchise before bringing out the big guns(Doomsday).