I remember the complaints from PAC-10 fans, how playing everyone in the conference made the conference look week. Nine weeks of the season you were playing a team that knows the other team fairly well, have a history with, and so you'd see a fair amount of upsets. Even if a team wasn't upset, often the game was tighter than the experts thought it should be.
By contrast, with a 12 team league you only have 5 games vs. teams you see every year. Additionally, you often skip a couple of the top teams in the conference.
I think, to a degree, we are now seeing this; that the Big 12 reputation is taking a hit because of the round robin schedule while, at the same time, the PAC-12's reputation is improving now that they are no longer playing the round robin schedule.