college football D1 has a format for a playoff, its called every other division of college ball except D1...but like travis said it comes down to money.
And money pays the bills for the coach, the heisman press team, the tutors to do the players homework, the money to give to the boosters to cover up your gun charges, the limo jamal and charliqua need to get to the games and so on.
I think it would be great to go over the book and acedemics of every program and strip out the cheaters and ban them from having a program for 2 years for each violation. That would be awesome.