This may seem pretty stupid, but please bear with me.
If a question gets badly downvoted, how can you make it a better question? (I.e. with fewer downvotes.)
I mean, if it's a dumb question to begin with - as in "first Google result has the answer" dumb - there's not much you can do to make it better. Deleting it would seem the honourable way out; but deleting questions is frowned upon. Oh well.
No, it's questions that need extra information to be answerable at all, questions that only describe the failed attempts at a solution rather than the actual problem, or where the OP, after getting very frustrated with hours of editing and debugging, just rants about the %$^*ing compiler instead of managing to enter a coherent story about what goes wrong. You know the type of questions, you've seen them.
A question of that calibre quickly gets downvoted in a hit-and-run way, and if the downvoters don't bother to mark it as a favourite (and why should they, for bad questions) they'll never know if the question was edited to improve its quality.
So, what can you do, as an OP? You can't notify the downvoters that the question is now better, because you don't know who they are. And you don't attract new views at all, because edited questions don't reappear in the front page if the scores are too low.
So in the real world, improving a question simply doesn't work. It does nothing.
Does anybody have any ideas on how to make it really work?
There is Allow an edit to notify downvoters: “I think I've fixed the issue now - please check”, by a very highly regarded user even, but it was declined.