I have a book somewhere that lists network nighttime programming from 1946 to sometime in the '70s. I haven't seen it (or thought about it) since I moved into my house. I'll have to look for it.
Programming was understandably thin during the first couple of years. The book includes the DuMont network, which I think was gone by the time I was born in '59.
Of COURSE there is a lot of garbage on current TV, but there are also hundreds of channels. I think we have many more programs of quality and distinction to choose from today than we did back in the 1970s.
It's great having channels like Bravo, Turner Classic Movies, The Food Network, The History Channel, National Geographic, Independent Film Channel, The Sundance Channel, HGTV.... I would never want to go back to having only CBS, NBC, ABC and PBS.
You have to remember that while we look back fondly at shows like The Beverly Hillbillies, Green Acres, I Dream Of Jeannie, Bewitched, The Brady Bunch, etc., they were panned as dreck by most critics in their day.