They're getting mad because the change is mandatory (you can't not fill in a name) and their policy isn't clear (it doesn't say you don't have to put in your le

They're getting mad because the change is mandatory (you can't not fill in a name) and their policy isn't clear (it doesn't say you don't have to put in your legal name.) Also "first names" aren't unique, but usernames are. People have been using usernames on the site for years. Why the change?