[MonkeyF0cker]

They show usernames for a couple different reasons, the main ones being: people like to return action to guys who have given them action in the past - seeing the names allows them to do that.

The other reason is it also helps facilitate guys trading action using the site chat-feature. If you see someone wanting SF 49ers for example, and you want NE Patriots, you can use the chat and say "hey man, I see you want the 49ers, I'll match your 49ers if you take my Patriots". Guys "trade" action like this often. Can't do that without the names.

Well, if they want it to be Mickey Mouse, then Mickey Mouse is what they will remain. An exchange with liquidity and scale wouldn't have the need nor the use for chat.

But of course this is bitcoin and fully anonymous, so you can have 20+ accounts under different names if you are worried about someone tracking your orders, and disable your chat.

Sure. But why should you need to?