A program cannot check if you've put in a retarded name without having a massive set of conditions. Even then, it's easy to bypass and slip through. Even a professionally built system like the XBox Live system, by Microsoft, can easily be tricked into allowing inappropriate and offensive names.
Then you'd need another check to see if there are any suspiscious elements that would indicate a multi account.
Then it needs to return the appropriate result, and either send one of the various e-mails for failure, or the acceptance e-mail and either activate or delete the account in the database.
The system also needs to be aware if it has just received multiple requests from the same person, and react accordingly.
And finally, if there's an issue with an account and someone comes to one of these forums asking why they were declined, the people responding to these questions need to dig through the server logs, find why the automated system declined it, and see if it made the correct decision, then help the person involved (which might require manual creation of the account if the automated system is going to decline it again). Whereas now, the person accepting requests is the same one answering questions and probably remembers WHY a specific account was turned down (at least for 48 - 72 hours).
But hey, if you're capable of programming an automated system that fulfills all the above requirements, go ahead and do so. I'm sure there'll be some CPs as a reward if it's useable!
____________"May the Grace of Ara go with you, and His Vengeance be wrought upon your enemies."
Only fools and children dream of heroes.