Background: Currently, my username (Patriiiiiiiiiick) is blocked on Wikipedia because it is deemed invalid. I've used this username for 15 years without anybody getting offended.
Suggestion: Users should be able to login with a user of their choice but the displayed screen name should be another string which could in turn be moderated. There should be a private and a public side of a user account. This would allow me to use the login name of my choice while using a screenname which is accepted by the community.