If correcting the grammar makes the questions easier to understand, I think the edits are worthwhile. If the question is easy enough to understand without the edits, I don't think we should do a lot of correcting because it gives a false sense of what level of fluency the asker has.
I view answers differently, and feel that the grammar should be corrected completely. When learners search for a question, they are likely to make similar mistakes to a learner asking the same question. When they are trying to understand an answer, it's easier for the learner to read text that has good grammar, spelling, and punctuation.
We have some very good answers from less fluent folks, and I think fixing them up is worthwhile. Fixing up the questions too much can lead to answers that presume a greater command of English than the asker actually has.
I'm editing this to bubble this discussion back up to the top of the active list. I'm seeing some questions being edited for style, and not to make the question's intent more clear. It destroys valuable information when someone "fixes" a learner's question, and while I whole-heartedly support significant copy-editing on answers, I really wish folks would show more self-restraint on the questions.