This is from a recent reddit AMA (ask me anything, which is a (usually promotional) candid interview done by anyone who wishes to participate) with Leo Laporte (formerly of TechTV fame):
Question: When did you know that TechTV wasn't going to survive?
Leo Laporte's Answer: About a year before it folded. I remember trying to tell the TechTV executives that we should target the 14 million computer programmers in the US with really smart programming. They told me that sponsors hate a smart audience and there was no future in smart programming. That's when I started polishing up my resume.
And there you have it, folks. Straight from someone in the business. Those "TV is dumbed down" people seem to have a point, and once again, it all leads back to money.