Sounds like there are lots of good reasons to change usernames but is there any good reason to change your username a lot? Other than safety issues, all examples given seem like rare events. Consistency is good. Seems like there should be an allowance to change your username maybe once a year without admin help and you could contact admin if there is a good reason to change more. I see no difference between regular users and curators. Both should have the same regulations to prevent abuse and prevent a large amount of unnecessary changes.