I wred the OP.
They have to scrape the bottom of the barrel. There isn't that much good documentary that they can show all new stuff, and for now (not everyone has TIVO) they have to compete with other channels on an hour-by-hour basis. Showing the same stuff over and over doesn't cut it.
Plus, there are special interests who invest money in making "documentaries" which they sell at below cost. Mighty attractive as content, to the commercial interests which are cable channels.
Free-to-air was only ever good when there were a limited number of channels competing for content. The cable providers still compete hour-by-hour, and as Springsteen said: "57 channels and nothin' on."
It will change, as more people divorce their watching hours from the broadcast hours, with TIVO or by getting the same content on the net, when they choose to watch it.
And the internet is something else entirely. You get what you look for, but you get it when you look for it. It's not so passive, you have to choose each time, and not just the least boring of the options. When you stop choosing, you stop getting.
