Actually, Congress has used this authority more than once:
http://www.eagleforum.org/column/2006/jan06/06-01-25.html
Yes they have, but only on important stuff like letting Tom Daschel cut some trees or clear some land that the enviro weenies could have objected to.
Clearly they have never went near the abortion issue, when equally clearly they could have.
Actually I think they passed legislation, not subject to Judicial review some 118 times.