The old bowl system was much more regional and tribal than it is now. If you were in Big Ten or Pac-10 territory, the Rose Bowl was the end-all-be-all. For more than fifty years, the winners of the Big Ten and the Pac-10 met in the Rose Bowl, so the pinnacle of those conferences was Pasadena. Full stop. Particularly given the way the MNCs were decided, the other bowls--and as a result the other conferences--really didn't matter as much. And of course fans of teams not from those two conferences probably didn't much care about the Rose Bowl, other than its nice time slot. None of their teams would ever play there.
I grew up in the Pac and went the Big Ten for college and the Rose Bowl was what we cared about. I watched the end of the 1987 Fiesta Bowl--I remember Penn State batting down Miami's desperate last attempt, but that's the only bowl game I remember that wasn't the Rose Bowl. I'm sure we watched some of the other bowls from time to time, but they just weren't that important because that's not where our teams played.
Particularly at a time when independent teams were large on the landscape and the Orange, Cotton, and Sugar had at most one automatic tie in, so Miami, Penn State, Florida State, and Notre Dame would play the top teams from the SWC, the SEC, the Big-8 or the Big East in the Cotton, the Sugar, and the Orange, and then the Fiesta, too. Frankly, the rest of the college football landscape had every reason to dismiss the Big Ten and Pac-10 and the inverse was true, too.