Perhaps it is because of its marketing and lack of a customer base? I personally have had bad experiences with racing wheels suring the days of PS2 and PSOne.

Perhaps no manufacturer had bidded for the specs to make a wheel or worst yet, the XBOX'S core may have something in there that makes it harder for makers of such add-ons to adapt to. What is worst is the fact that XBox may be have a steeper spec price. (game manufacturers, add-on makers have to pay their due to make stuff for game platforms and not the other way around....no joke!)