College football doesn't host playoffs. The "championship" game matches the two highest ranked teams at the end of the regular season, based on a more than usually uncertain ranking system (since some of the highly ranked teams will not have played each other). Sports Illustrated just published a story, before the championship game, saying that some of the early bowl games had low Nielsen ratings (which measure television viewership): Ratings are proof the addition of fifth BCS game officially a failure. The article notes "By removing the top two teams from the existing BCS bowls (Rose, Fiesta, Sugar and Orange), the remaining lineup gets unavoidably watered-down. "
Utku Unver and Guillaume Frechette and I wrote a paper which showed that (under earlier versions of the BCS system) the championship games drew enough extra television viewers to make up for the lower viewership in other bowl games that (consequently) had neither the top nor second ranked team playing in them. (See also this interview about the origin of the BCS system (to which I devoted an earlier post).)
So the BCS system may have watered down the rest of the bowl line-up, but in terms of incremental revenue the NCAA is better off with the BCS system.