Out of curiosity, is it possible to change usernames without registering it with a new account? I'm pretty sure this is a huuuggeee hassle, but I thought I'd ask :)!

This should answer your question, as quoted by the Need Help? description ^ ^ ;

"Have a question about the site? Need to talk to Guild staff? Until I have a better solution, you can come here to get help. (Note: No more username changes allowed. We don't rename topics. We don't delete roleplays once other people have posted in them. There are exceptions, of course.)"

aka: No. They were doing it at one point early on but not anymore.

^This. The exceptions being typos and misspellings.