I was just reading an article in the New York Times about how many shows are killing off main characters and listed some shows that have recently done it.
The L Word
One Tree Hill
...and coming soon
When I look at this list I can't help but think that there are only a few of them where it really makes sense to have a main character killed, not because of the demographic that watches the shows, but because of what the shows focus on. I don't understand why so many people die on ER. Mark thinks it is the most fucked up hospital in America. I don't understand why anyone would die on a show about housewives (though, I have never watched even a minute of the show).
The reason I read the article at all, titled As the Plot Thickens, No One Is Safe, was because Tony, a main character on 24, died this week. Main characters on 24 have been killed off pretty readily since the second season (or the last episode of the first season).
Sarah Gilbert's Character(S2or3)
The majority of my point here is that killing off main characters is not some sort of new phenomenon this season and that some shows have a built in reason to kill them, and some do it for ratings.