As A web programmer I do understand the difficulties behind allowing username change.
but what I can’t understand is why not keeping the usernames in background and displaying our real names or our companies name (and even making the number of changes limited to 1 or 2 times). and like that we can fix that username change issues.
many did choose the username cos it is the easiest one to remember(my case) or for other reasons other than being a brand.
and I think the support every day receive hundreds of tickets asking for the ability to change username.
its not fair that a user drop up to 5 years of reputation to change username.