Subtle changes, bugs and feedback

Yes, of course.

But depending on the circumstances they might strongly feel that their username history should be wiped.

Real life examples I have handled on LFGSS and Bowlie:

1. A US person lived 20-25 on one of the forums, and later found a work opportunity with the CIA (I shit you not), and knew that they would conduct a very deep background check. She wanted various posts deleted, but more importantly the username to be eradicated.
   
2. A UK person found that they had libelled/defamed another person, and felt that for their own future precautions that they should not be traced so easily by a username they had which in part identified them.
   
3. A UK person originally registered with their real name, and gained a stalker elsewhere in life. They urgently and desperately wanted to ensure that the stalker would not trace them here.
   
4. A UK person who was working in a locked-down office environment was traced to the site by their boss, who didn't yet know which account was the one they were looking for, and this person wanted to remain part of the site but needed to be sure that the boss did not find them.
   
   

Those are just a handful of real world situations I've dealt with that have required that the username history shouldn't be kept or shown to others.

Yes, people could create new profiles, but most people don't seem to be savvy enough to think of this. I had thought about displaying username history originally, but felt the system should look after privacy by default.