Post deletion has two prime issues:
- It is disruptive and obfuscating when people have already replied. Replies are a continuous stream and deleting a post part way through a set of replies is bad form. THN Moderators generally avoid deleting posts and instead focus on closing threads if something needs shutting down, with the exception of illegal or substantially offensive content (e.g. pr0n).
- Post deletion can break threaded viewing. Some users, notably Admins, use the Threaded View. If a post is deleted part way down a thread, that view breaks. Sure, it's possible to switch back to the default Linear View, but that's both a pain and not necessarily obvious that posts are missing.
The first issue could possibly be managed by a watchful moderation team and soft deletions (i.e. they can be recovered by a Mod/Admin).
The second isn't resolved that way, though.
In summary, deletion isn't going to be turned on for users without some changes in the way vBulletin works. Report Post can be used to identify a post where action is needed, be it moderation, deletion or whatever.
Incidentally, user edits can be reversed by an Admin so the fact that you can edit your post to nil (which is generally considered to be bad etiquette) isn't a serious issue.
