Most of the Pac-12 teams suffer from the same problem.
Only three of the teams play in a state without a NFL team (U of U, OSU, UO).
Two more teams play in areas that aren't shared expressly with an NFL team (U of A, Wazzu), but have their fan bases primarily in major markets (Phx and Seattle).
I honestly couldn't tell you how much the Portland radio talks about the Ducks, but I know from living in the Bay Area for a time that KNBR doesn't touch the Card or Bears really at all. Giants, Warriors, Niners dominate airtime, and Stanford has been elite for more than half a decade (and generally respectable or better for a century). They mention the time and opponent in the games of the weekend, but that's about it.
Denver, San Francisco, LA, Seattle share the issue touched on above- they're full of people who didn't grow up there, probably didn't go to school there, and even if the first two are true, don't care about CFB as much as the NFL. Denver is full of transplanted midwesterners with CFB loyalties, just not to the Buffs.
That said, once the power balance evens back out from the current lopsided position- the Broncos just won the Superbowl and the Buffs were god-awful and have been generally for a decade)- there's no reason why the Buffs can't have more airtime.