It was announced last week that ratings for all of the TV premiers were down from last year. Can't say I'm surprised. Did anyone really expect them to go up?
One reason they dropped: the rise of TV on the internet. Hulu has shown a big increase in popularity over the last year, with NBC being a major backer behind it. More people are shifting towards watching TV shows at their convenience, instead of only at a specific time slot. I believe there is a correlation between the rise in popularity of the DVR and internet TV. Both let you watch almost any show whenever you want. While DVR lets you skip commercials, internet TV cuts down on commercial time significantly.
Another reason: It is free. Why buy the cow (cable subscription) when you get the milk (tv shows) for free? When people started sharing CDs online illegally, the labels went after them. The TV networks are doing the opposite by offering up their content online also.
This is a step in the right direction for TV networks. They are embracing their customers and adopting to what they want. They learned from the mistakes of the music industry and embracing change.
WSJ has more on this here.