Every sport has it's own unique attractiveness. College Football's is the immense importance of each game for the top teams who are in the Championship hunt. In addition, the sport offers so many interesting and complex disscussions/arguments that are apart of American sports.
If there was a playoff system, then College Football would become much more like all of the other major sports where the regular season is de-valued, and the top team simply try to make the playoffs.
In additiion, it would still be unfair every year because there will always be teams, some undefeated, others clearly better than those chosen for the playoffs, who will be left out.
Right now, the SEC championship game really matters. So does the Big 12's. In a playoff system, they either won't matter very much; or if there is a guaranteed spot, that would leave out clearly good teams.
Leave the sytsem alone, enjoy the games, and enjoy the debate.