Twice now, I've seen my submission titles edited by someone else (probably Graham or his admins, if he has any for this site).
Both times, the edits were innocuous (the first one improved the title ever so slightly) but unnecessary.
It's not a huge problem, but it is a bit annoying.
1. To keep the site clean (no spelling mistakes, gratuitously long titles, SHOUTING!!!, etc.)
2. To keep titles fairly neutral. People have a right to say what they want in comments, but because a story can only be submitted once, if we didn't edit submission titles, the first submitter could put whatever spin on the story, and all readers would have to read it as that.