The problem: Poor quality questions get viewed by a lot of people and that's a waste of time.
At MSO (Meta.StackOverflow), people believe that downvoting is good. In a short period of time, these questions are downvoted 'into oblivion' (10 downvotes or more).
However, I believe it is negative feedback that doesn't help the OP (original poster) to improve the quality of the question.
The solution: Hide downvoted questions. Suppose a question is downvoted three times in a row (no upvotes). The system then hides this question from the main view, but the OP can edit the question to improve the quality. After the edit, the question will be visible again (and hidden again after another three downvotes, etc).
It would be great if one of the downvoters would provide feedback to the OP, but that's another story.
Do you think this could be useful at StackExchange?