As I said earlier today, don't demonise the messenger! I would not advocate leaving the TV on as background but there are plenty of educational, informative and entertaining (yes, entertaining!!!) programmes on that most kids could benefit from watching. I remember learning a lot from Blue Peter in the 1970's and I loved Newsround, it engendered in me a desire to know what's going on and I watch the news and read a paper every day. I have a friend who has a TV but no aerial and just lets her DSs watch videos for about half an hour a day, which she watches with them. She doesn't watch TV herself (obviously) but also doesnt read a paper and hardly listens to the news on the radio. She's an intelligent, well educated person but didn't even know last week that the pope was ill!
Through TV my DS1 has learned about the stars, dinosaurs, different countries, the fact that the Tsunami happened and people were killed - prompting a discussion about life and death which I think helped him understand the 'circle of life' - as well as watching some fun kids programmes which he enjoys (AND the Simpsons, which we all enjoy!) He's never watched Power Rangers and I doubt if he even knows there's a programme about them, but he has at least 6 of the Power Ranger dolls.
TV is one of the most powerful media for communicating with other people. It shows children and adults a life that is different from their own. It makes them aware that there is so much more on this planet than just us. I think that to deny our children the opportunity to learn from it on a point of principle is plain wrong. There is an on/off button and there is such a thing as choosing the programmes you want to watch and switching off when you want to live in the real world. Would parents who deny thier kids Tv also deny them books because of Jeffrey Archer?