Can't register username over 12 characters

I'm trying to register, but I can't enter username over 12 characters (registration page says 6 to 30). The field has a 12-character max length set in the HTML. You might say, "just use a shorter name". I use LOTS of different sites, though, and would never be able to keep my logins straight if I had to use different usernames.

A login that is infrequently used, and doesn't have a predictable, memorable username is pretty much ... well, useless.