I have a TV and only use Netflix (streaming and DVD). My 3 years old kid loves Stephen Hawking's Into The Universe, Ocean Documentaries, a few cartoons that actually deal with important stuff (not to be afraid of dark, sharing, etc.). I watch 2 to 3 movies a week. But the iPad gets most of his attention. He loves SolarWalk, his favorite...you can explore the galaxy and solar system. He asks me a lot of questions. Loves to draw black holes, the sun, and the different planets. Yet, most of the time, he's at school, drawing, playing with water, "cooking".
What I think you describe has to do with the average content, which is....pretty average and will make anyone dumb. Even just watching normal TV will kill your productivity by the sheer amount of ads.
I think you can't Palme the TV. Or the tablet. Or the books. You need to blame people content choices. And about balance or moderation.