Not only does it take more effort to pose a good problem here than asking questions on most other sites (not to mention how hard it will become to come up with good ideas once a lot of problems have already been posed), it's also much more selfless to ask a question:
On most other sites the primary reason to ask a question is because you want to know the answer. So the primary benefit you get for asking the question is finding out the answer. Here the main benefit of posing a problem is that the users have another problem to try their luck at. So basically the answerers are the ones who most benefit from a question.
Further meta.stackoverflow also gives you 10 reputation points for question upvotes for similar reasons, so we wouldn't be the only exception to the rule.
So in short: Yes, I'm completely in favour of your proposal.