Both of them would have a much higher chance of making the playoffs by staying in the Big XII, and it seems like they both had enough money (total athletic budgets from all revenue sources) to be competitive, even if the TV revenue is higher in the SEC.
In the era of the 12-team playoff, it almost seems like a good strategy to be a big fish in a little pond, win the conference every other year, and in years that you don't win the conference, likely get an at-large bid anyway.