Moving this over to the Inputbox board, as I believe you are proposing a suggestion to the site. c:
In many ways, I like this idea. Especially for floofs who may enjoy changing their usernames but still want people to recognize them under a previous username. I've seen a few folks write in their previous usernames (ex. "previously ____"), so I definitely think it could be utilized. The only issues I could see with this change is if 1). The previous username were something inappropriate and changed due to a necessity to make it appropriate, 2). A user changed his username in an attempt to avoid being recognized (whether due to privacy reasons, in-game harassment, etc), or 3). dislike of the old username, possibly if outdated/embarrassing to the member. Initially, I thought it could be helpful to allow the user to type in the name of his username, but this could cause a form of identity impersonation. It would definitely have to be automated to show the actual previous username (or the user choose from the site-generated past usernames of theirs)? There are some complications, but they may be able to be worked out.
Ultimately, it's up to Raz to see if he can implement this, but you have my vote for this idea. c: