I was thinking because they would need to go all out to get to that playoff to get the money paid out to the participants.
Take Iowa & Wisconsin for example. In the current system Kirk knows that a 4-4 B10 record, a low tier bowl win in Tempe and its a good season. He goes home happy, so does the AD.
Wisconsin while in a much bigger bowl game goes home win or lose, great season but with about the same amount of money that Iowa does because of revenue sharing within the B10.
In a playoff system Wisconsin goes to the NCAA playoffs, gets a huge payday all to themselves, possible host of a playoff game or two which means more money, and has a shot at a legit NC.
Iowa gets left out of the playoff, goes to a meaningless bowl if bowls even survive in a playoff system and goes home with maybe 1/10 of what Wisconsin does.
That is the motivation. Be great or else. The current system promotes and rewards average performance. A playoff system rewards greatness.
But you are correct. A playoff system would very likely put Iowa on the wrong end of the power shift. They would still rake in plenty of money from the BTN though.
I don't have any issues with people who love the bowls. Tradition is important and tough to break from. I just don't agree with it. It is grown stale to me.