You win it or you don't. Winning the national championship is, I would argue, the ultimate goal of a CFB sports team. it doesn't matter who is on the other side, it doesn't change that it was a national championship. It is equal in value to other national championships. Winning the NC isn't the same as determining who truly was the "best" team in a vacuum.
Since winning the NC is the ultimate goal, then the game played to determine the NC is easily the most important game.