Correct me if I am wrong, but I think Windows 7 is the only operating system out there that requires a hint for the first user created on the system (have not had a chance to check out Windows 8 Beta). Why does Microsoft insist on requiring a hint for what could be seen as the root user? Of course you could always put something bogus in the field, but why require a hint?
Because these devices are for mass consumption. Security must fight with dealing with a spectrum of users and usability. It is possible that users will only ever set up the first user. Let's face it, a good hint can be useful if created properly. However, bad passwords are more common than bad hints.