I think you guys should bring back the old username registration (may include ^ or - or [ ] and etc).
The new registration sucks.. (Username must only includes a-z,A-Z, 0-9, underscore (_) and dot(.) only !)
p.s. Think this way, you have a team and you wanna tag up using ^ or - or [ ] and etc. BUT YOU CAN'T BECAUSE OF THE NEW REGISTRATION. THIS MIGHT SOUND LIKE A MINOR PROBLEM, BUT WHAT IF YOU ALREADY HAVE A TEAM AND THE TEAM IS TAGGED UP USING ^ or - or [ ] and etc? IF ACCOUNT SPOOFING IS THE PROBLEM, THEN JUST DON'T ALLOW | . SIMPLE