If the Big 12 misses the playoff again in the next couple of years due to the lack of championship game, I might be for expansion. However, if you can have a conference championship game to rectify that issue with just ten teams, there is no reason to rush into expansion.
The league will have to push a few teams to up their ooc if they want to stay at ten teams and be in the playoff regularly. Loading up on a bunch of weak teams at home to start the season isn't going to cut it, especially in years the conference is down.