"Kids should be learning how to paint with oil paints or watercolours, not snapping together these pre-painted jigsaw puzzles!"
I think the real difference here is that we've transitioned from more of a mixed/manual labour economy to a mental/emotional labour economy. People get off work and they just want to come home and do something relaxing and not mentally taxing. Putting together a Lego set is like that. It takes more thought than watching TV, but not much. Coming up with something interesting and creative from a bucket of random Legos is different, and most people lose interest.