But I wouldn't delete it, it's just a waste of time and it can be useful for various things to not delete submitted posts. It's part of the history of your account, so why delete it?
I would agree with regular posts made in general sections of the forum, deleting such (on a large scale) may skew a thread as the posts may have been quoted by other members involved in the discussion. Bounty reports however are not discussions and are unecessay imo, as the managers could use an external service like Google forms and check manually rather than walls of quotes and re-quotes, but they go for the easy way.
Deleting them wouldn't affect much and would help unclog threads, also there's the privacy issue as some of these users enter social media campaigns on the forum using their actual profiles, this could lead to their offline identity being linked on the forum later on.