Without advertisers, what pays for the show?
Subscription, like cable channels. Like HBO, Showtime, etc.
I know, I know... network is free, etc. etc. but like Katiemac said, the advertisers are calling the shots, and quality shows suffer and the reality shows thrive because everyone is following the dollar. The advertisers are paying, not the viewers. Like Katiemac said, networks have less incentive to let a show grow (many shows are taken off even before the season is over) -- something like 30 Rock or the Office is rare (they are critically acclaimed but not rating champs) -- advertisers are impatient, and the networks follow their lead.
But when economy is rough, the quality shows go out the window because advertisers can't pay, and quality shows are expensive to produce. What's left are cheap-to-make reality shows or formulaic shows that cater to the lowest common denominator. Or they crank out 20 new shows that smell the same, hopeful that one would stick and become a bona fide hit to pay for the other crappy shows.
To me, the "free network" advertising-based model is archaic anyway. It's the same as the newspaper model, and we all know newspapers are dying. Especially in a down economy, the advertising-based model is one of the first to suffer. People want quality entertainment and they're willing to pay for it -- for a reasonable subscription fee, for example. Music subscription/download sites are thriving now. People want quality, and they want choices. I'm willing to pay $0.99 for a song I really like instead of paying for $15 for the entire album, or trying to catch it on the radio with lots of ads.