I read an interview somewhere with the BSU athletic director that the reason for that (high profile teams not wanting to come to Boise) is because of the capacity of Bronco Stadium. It only seats 33K, so there's less money to be made for the visiting team.
Personally I think that's a crock; the Alabama's and the Texas's like to schedule creampuffs out of conference so they can pick up an easy win.
It is a crock. That is why you schedule a home and home. You get the all the money when they come to your place and they get all the money when you go to theirs. I would think BSU would be an attractive draw for schools that don't sell out early season non-conference games.