One real example: I posted a question and, after a first comment, I decided it needs a rework. I can not do it immediately, thus, I've deleted the question to not waste the time of other users.
I'd like to edit it and, after that, undelete. However, the system only allows me to edit an undeleted question. If the undelete is done before to the edit, again some users can read the initial version in the time it takes me to improve the question.
Why are we not allowed to edit deleted questions?