Bottom line, I think, is that forcing people to discuss (not just summarily up or downvote) is really important to getting meaningful content. It's fairly easy to see when someone is talking out of their ass, but it's much harder to get a read on how intelligent an anonymous (or even attributed) vote is.
Gaining reputation points is a wonderful short-term incentive for contributing. Otherwise why waist time instead of working on something fun? (and good answers take a lot to write)
Obviously there's the problem of people "gaming the system" to earn more reputation and you do whatever is possible to prevent that, but there's no reason why people can't be there for both the reputation points game AND to spread knowledge. The problem now for Stack Overflow (as I see it) is that it's reached a level of saturation where it's difficult to do either.
edit: to clarify, I mean he cares about how reputation is handled, not necessarily about his own reputation.
http://stackoverflow.com/questions/2264267/generating-a-quiz...
http://stackoverflow.com/questions/2264286/generating-a-quiz...
I had around 90 questions when I quit. The way the game was set up, you always got a lot more points for answering questions, then getting them upvoted. In general, you are going to get more votes in the most popular topics.
Reputation is also a currency. You can spend it to get better answers to your questions, 50 points minimum. My reputation was probably between 2300-2500 before the devaluation. I guess I would have lost half? Not sure. At any rate, where StackOverFlow could have been really interesting is moving beyond the simple questions and solving specific, but a more complicated, questions. If you don't take the time to be specific, someone will just give you a link to another site. That gets upvoted a few times and your question is done.
Hopefully, someone will come up with a better model. I'd do it without rep, but I like the economy aspect. I think it draws in people. People will game it, so design the model to get the desired results: Great questions and great answers.