The problem with rankings and playoffs is that they are designed to hype the game and make money. Period.
The only reason that BYU and Texas Tech were upsets is that they were hyped up in the standings in the first place. I love watching BYU and Bear Bachmeier. They are a fun and talented team, but not nearly so strong, fast, big, and skilled as a true top ten team. Does anyone truly believe they could compete with the likes of Georgia, Ohio State, Indiana, Alabama, etc.? Yet, they were ranked above those teams.
Each year, there are 10 to 12 teams who truly could compete for the championship if it depended on winning more than one game in a playoff. Including teams like James Madison, Tulane, BYU, etc. in a playoff has nothing to do with determining a national champion. It's just about money.