Just out of curiosity I anonymously clicked on the "improve this question" link and see this message:
We welcome all constructive edits, but please make them substantial. Avoid trivial, tiny one-letter edits unless absolutely necessary.
In Wikipedia it makes sense to change the meaning of the article if this helps Wikipedia. StackOverflow is different. The emerging consensus seems to be: You only "fix" a question: typos, broken links, formatting, etc. You don't "improve" a post. If you want to change the meaning, write then a comment or post an answer of your own. Am I right or did I misunderstand something here?
I see many well-intentioned edits being rejected as invalid edits. I think this is because beginners don't realize the difference and are misled by the word "improve" and not guided thereafter. I propose a different wording. Perhaps "fix" instead of "improve", and perhaps an additional sentence
Avoid changing the meaning of the question. Please write an answer of your own or post a comment.
at the top of the edit window?
This applies to "improve this answer" as well.