That's not quite true, theymos also does manual name changes, though you are very unlikely to get one.
It's mainly if a company rebrands (for their forum rep account), or for high ranking/long standing users of the community.
So someday I have a chance to find an alternative username. My problem is, I can not find any other name except my current one. I kinda fall for it. I have been using this username from long time in everywhere.
Hold on... I have a new one in my mind now, I am gonna keep it secret
PS: Thanks Lutpin, good to know this information. I always thought same like TryNinja.