An eight-team playoff would have been injurious to major college football in 2015. Anyone who says otherwise is not interested in allowing the results on the gridiron determine the national champion. A quick look at the teams ranked #5-8 by the CFP selection committee will make this clear to the impartial college football observer.
#5 Iowa was well aware of what was at stake when they played Michigan State for the Big Ten Championship. They lost and were therefore rightfully disqualified from national title contention.
#6 Stanford, contrary to popular opinion, was not merely the victim of cannibalism within the PAC-12 Conference. They also lost to arguably the fourth best team in the Big Ten.
#7 Ohio State essentially has the same plight as Iowa. Their defeat at the hands of the Michigan State Spartans cost them the Big Ten title and consequently the opportunity to defend their national crown.
#8 Notre Dame's loss to Stanford logically placed them below the Cardinal and by the Transitive Property justly eliminated them from the playoffs.
All four of the teams listed above were discarded for losing games on the playing field. To allow said teams to play for the national championship would undermine conference championships and the outcomes of the regular season.
The current generation needs to be constantly reminded that the origin of playoffs and the literal definition of the word is a set of one or more games used to identify the champion of an organization in the event that the games of the regular season have failed to do so.
The bottom line is that a larger playoff field places teams on the same level who may be far apart in regular-season success and yet threatens both with the same punishment for postseason failure.
It is disingenuous to argue the equity of a system that disqualifies the 2007 New England Patriots for losing one game and then scream "Injustice!" about a system that rejects a one-loss Ohio State team. And no it does not matter that New England's loss was in the Super Bowl and Ohio State's loss was in the regular season.
Placing more value on contrived "playoff" games than regular season games is a completely arbitrary approach and however large the crowd that promotes its application, it does not refute my thesis.
College football enthusiasts may honestly desire a larger playoff because it adds more excitement in December and January and others may wish for a bloated playoff field because it simultaneously bloats their wallets, but the forthright fan will at least admit that it would not make for a more worthy champion in 2015.