Don't you think people could use this to delete anything they don't like, even if it's not bullying or otherwise against proper conduct? I believe there is a button you can use to report a comment. Of course, not everyone wants to delete something simply because they don't like it, but they don't want to report it because it's not really against the rules...

Deleting other people's messages is pretty 'controversial' (lack of a better word). People are able to delete comments on their own projects, but in the forums you're not able to delete replies from others.

I'm personally in favor of members not being able to delete messages from others at all. If you don't like a message that isn't really against the rules, people should just block that user (I don't know if blocking works with wallposts atm though). Blocking atm just stops the user from posting messages on your submissions (and possibly wall posts?), but it should probably get expended a bit with all this new stuff on the site.