Which is the ability to play in a conference race. Even if BYU's schedule went from 5 P5 games per year to 10 or even 12, that would still be inferior to Utah's situation because of the lack of a conference affiliation thus nothing to play for after the first loss. When you are in a conference, every game matters to get to bowl eligibility, then for conference standings and bowl affiliation. Plus you are playing the same teams so you build up natural rivalries. BYU's games are cosmetic after they've lost one and are out of the New Years Day Bowl discussion because 11-1 and 6-6 are the same; both get you to the Miami Bowl or whatever.
This is why the MWC is preferable. Even if the competition is lower, a Nov game against Air Force or Wyoming means more than a Nov game against Cincinnati even if Cincinnati is actually a better opponent, because it is the difference between first and second or third in the conference and going to the Cotton Bowl, Vegas Bowl or New Mexico bowl.