Behind our usernames, there's user number. I'm sure dang & co, would let you rename yourself if you asked them nicely.
However adding it as a option, raises the problem of people trolling the site, and then quickly changing their username to dodge the fallout - some sites have icons to show that a user has recently changed their name, some have a username history on the profile - it's not a trivial problem to solve.
Yeah, some places have an unwritten "just write us and we'll do it" policy. It's nice to know they're up for it, but the cognitive load of reaching out is like 100x higher than just putting it in your preferences. I know there's no good solution here though, so I guess i'll just shout at the sky.
However adding it as a option, raises the problem of people trolling the site, and then quickly changing their username to dodge the fallout - some sites have icons to show that a user has recently changed their name, some have a username history on the profile - it's not a trivial problem to solve.