People are looking at these issues from very different perspectives. But these actually aren't mutually exclusive; there's another dimension to the problem that hasn't been raised.
Role of question vs. answer
Start with the question, that's what gets the ball rolling. It provides the framework for the answers to be created. Once the answers are there, the answers are what contain the knowledge in our knowledge base.
If an answer isn't self-contained, the question provides context. But a well-written answer doesn't really even need the question. With great answers, the question becomes mainly a tool to help organize and find the answers. But searches can find the answers directly.
So the relative importance of the question vs. the answers changes after the answers come in if the answers are good. And that change in importance means that our strategy for making decisions about the thread should change with it.
Strategy vs. poor questions' changing problem
In the absence of good answers, a bad question doesn't add value to the site. It either can't be usefully answered and is just clutter, or it can attract low quality answers. In this case:
- Clean it up or clean it out.
But, if it attracts good answers despite itself, the problem with a bad question becomes largely esthetic. The question is the means to the end, the answers are the end. High quality answers (that are on-topic), are why the site is here, and those should never be discarded on the basis of the question being poor. So what can we do in that case?
Improve the question. Questions are often poor because people can't imagine how they can be usefully answered. The answerers have figured that out. The answers frame and focus the question in a constructive way so that other readers can recognize the potential that was hidden. So it can be easier to improve the question after great answers have been posted (and that is completely different from rewriting the question to fit the answer).
Ask a new question and post the answers there.
Lock the thread as a last resort if we can't get the question improved or replaced.