I recently posted a forum thread here about people's thoughts on username change. I find that a lot of them would like it, but know that deviantART has openly stated that they will not transfer anyone's content over.
Relatively recently, Nobody, a deviant who wants to change her username posted a deviantART Suggestion here which got a Daily Deviation. I was a suggester, which shows that I am in full support of this idea.
On this Suggestion, I commented the following:
"I like this suggestion, but I know that dA's thing is that they don't want to confuse people by having people's profile links broken. So, I was thinking that instead of putting your old username back open for anyone to get, you pay the fee to have it disabled and whenever someone goes to that link, it redirects to your new page (like with Nobody redirecting to Nobody)!"
You can see the comment thread