Let's be honest - neither team has anything to gain from playing the other. It's not going to get either into the playoffs (and getting there would just mean getting stomped by Bama, Ohio St, Clemson or Notre Dame) and runs the risk of missing a New Year's Six.

If you're going to take a risk like that, there needs to be a corresponding reward. Playing Oregon or Oklahoma or ... apparently Northwestern moves the needle/perception more than beating a good G5 team or a bad/mediocre P5 team, whether or not that's "fair"