That completely isn't true. Rivalries are built around the idea that both teams get impacted by whether they win or lose. Look at Michigan and Ohio State. Those teams hate eachother, but what makes the rivalry special is that in years past, each team has ruined the other's chances to win a national title by beating them in the final game. It adds more to the rivalry and really takes it to a whole different level.
Now, all of a sudden, because of some stupid 8+ team playoff, no matter who wins, they both get in the playoffs and even worse, they could face eachother again in the first round, effectively making the 1st game COMPLETELY worthless.
But ya, that wouldn't hurt a rivalry or make regular season games less important. Just wait until you see teams resting their starters like in the NFL because they are preparing for the playoff. Then you will see some great college football action.
Continue to think that college football is the same as every other sport, all it does is show how ignorant you are.