competition, beat a couple of marquee teams in the nonconference, and then get to NY bowl games. As an independent, BYU could schedule down more and fill up with non P5 teams. They could run the table with such teams, and then still have access, albeit less access, to those games.
So what the MWC offers is a little better chance of getting into the New Years bowls and the chance to play for a championship - probably for less money. The MWC right now is a heck of a lot worse than it was when Boise had their run - the schedule would be atrocious. No thanks.