deviantART introduces username changes 12 years after they were requested - Yay! They're for premium members only - [insert flame war against dA admins here]
The reason is, deviantART has bills to pay just like any other site on the Internet. Not to mention that they employ full-time staff as well. It's a little unnerving how so many people think that it's just as free to run the site as it is to go on it.