UPDATE: You can still get a Horsebanger email account.
Manually creating each and every account is time consuming, but necessary to keep out the type of people who would really bang horses in real life (people with malicious intent).
So far, 1000+ people have requested a HB email account. Simply put, I do not have the time to continue giving out emails 24hrs. per day.
Creating a new account is not 100% closed down. There is just more of a focus for providing free HB emails only to people that REALLY want one.