Why are deleted questions still visible to the created users? Does it have any usability? Can a user build upon the question, modify it and repost it as a new question or if he changes the question and request for undelete(there is an option for undelete), it will be active again?
Essentially, if a user comes back to a question that has been deleted, they can see it was deleted and see the comments and close reason for the question.
A recent change enabled this for low rep users (as +10K rep users and moderators could already see deleted content), so they can go back to their question and instead of getting a 404 get at least some information that explains why the question was deleted.
The idea is that if they can see the comments and close reason, they will know what happened, instead of wondering how come the question they had asked is gone.