Re: Overview of recent username changes in Bitcointalk
Are these changing username is based on how much of their contributions inside the community in order to be given a chance by theymos?
theymos changes usernames only when he is convinced with their PM and would consider doing so only he does know your username to some extent. alia changed their name from alia_armalle (not sure about the name) by sending a message to theymos and he has said it would be done after going through the trust scores as well. So probably its kind of either your request of changing username may get accepted or rejected.Or is it because they paid bitcoin? 
Mods are the ones who can change their usernames now and then without paying btc (Donators and VIPs)It is no surprise if there is an increase of change of username request in the community.
AFAIK SMF allows changing of display names, but theymos changed the rule for usernames when there were scams going on with these changed usernames.See this :
Done. Now only moderators, Donators, and VIP members can change their names automatically. Other members should contact me. I'll probably ignore your request if you have less than 50 posts (unless your posts are very good).
This was way back in 2011, then it was changed to the fact that forum users with good reputation can change their usernames if they feel like.
...snip...
Added. Thanks