its a requirement in some forms of auto-x.
a lot of people have seen this video:
http://www.youtube.com/watch?v=kyMDNzhfwn0
In that video, had the driver had extended studs, the wheels would have knocked around for about 5 minutes before falling off. But thats a little impractical, because that was user error that caused that accident. It is possible, when using aftermarket wheels for the lug nuts not to seat correctly and back out with heat from the constant pressure of turning leaning, and braking.