Their footprint just isn't big enough. Sure, they have the Cali market, but look at the rest of the states. Combined population of WA, OR, and AZ is less than 10M people. Throw in the rest of the western states and you probably don't even get to 15M potential viewers. I'll bet out of the P5, the P12 has the smallest population by a lot. Who is going to pay $$ for a sports specific network that reaches so few viewers? It is one of the reasons the MTN fell so hard on it's face.
They could broadcast earlier, but nothing before 2PM EST, and at that time slot, you've got all the primetime games of the B12, B10, SEC, etc. There are just too many people east of the rockies for the P12 too compete at those timeslots. Other than USC, does anyone east of the Rockies really want to watch ASU vs Utah, Oregon vs Stanford, etc.?
I am not a Larry Scott fan, and it may be too much to say he saw things playing out this way, but the Pac's inability to get outside their current geographic footprint really hurts their future. Hires like Riley are a good step in the right direction, but the days of the PAC10 and the Rose Bowl being primetime football for the nation or moving further back in the rearview mirror. Still a major conference, but I think their impact on the game, the polls, and playoffs will be the least out of the P5s going forward. They will still have a strong team every year, but top-to-bottom the league just won't get to the other P5 levels. B12 has its work cutout for it as well, but has a much stronger geography to work with, better overall depth top-to-bottom that will help raise more $$$ and, I think, gives the B12 a better shot at staying on par with the rest of the P5 compared to the P12.