According to Berry Tramel's article (newsok.com), it's because the schools don't want to jeopardize attendance during the regular season games, and the post-season revenue couldn't offset the loss of regular season revenue. Really. The article does remind us that while the NCAA controls college basketball, college football is controlled by the university presidents. But the piece doesn't explain how a small (4-to-8 team) playoff would ruin the regular season any more than the current roster of 32 bowls games does. Or could do any more damage to the sport and its revenues than is done by have the champion crowned by a vote of panelists rather than earned on the field.