I think the issue is more about why we downvote, and I would put money on the reason one person does is different to another!
I think if it was about showing disapproval of poor questions (or vice versa), then after we downvoted, and an edit was made to the post (to improve it) I would expect to be notified, so I can then remove my downvote (or upvote) accordingly.
This doesn't happen (at least not for me) which would imply this isn't meant to happen. Therefore I don't think that is what downvotes are for (or if I'm wrong, then maybe the system could consider this).
I think if the question is poor, we vote to close!
If the question is rude or lazy (such as do my work now, or no effort to format it or show examples) then that is worth a downvote. Of course, even rude questions are some times just due to the persons first language not being English....