We have a few names around with - in it and like 1 name with a space in it, which looks decent, but it's pretty hard to type and all other things would probably look stupid.
I don't think usernames like €0,50 (50 cent pls) would look ok in this game.
If you do that, we then get names like:
-xXX|Sw3gmast3r420blaz31t360n0sc0p3|XXx-
Now, do you want to type that into the chat to yell at the noob who has that name?
Bad Idea is my point.