Suppose you had a question, and you really want a good answer that would solve your problem, but noticed it was already asked by someone else. Now, a lot of answers had been posted and upvoted, and maybe one was accepted. However, none of the answers solved your problem. The system does not promote the question very much because it is not considered "unanswered", and a lot of users who would otherwise bother to give a correct answer will probably skip the question completely as there are already many highly-voted answers.
Now, what should you do in this case?
One idea is to ask a new, completely identical question, but now you're in control to decide when it is answered. But would that go against SE policy?