Perhaps because they were highly, highly experimental, the early little kids' edutainment shows, like Sesame Street and Mister Rogers' Neighborhood, just struck me as much better because they didn't insult children's intelligence, spoke to them as full persons, and had relatively rich and complex imagery, music, story, and humor. Which is why they're so watchable and beloved by adults.
And then Elmo happened and then Barney happened, and things have been on kind of a downhill slide into brightly colored, C-major MIDI music Cocomelon happyland.
Cocomelon are all sung in this weird smug condescending tone. It's really unpleasant.
Compare with Pokémon Kids TV, which sounds really cheerful, and you can hear the singer is really enjoying themselves. Also mostly the same classic children songs, but so much more enjoyable to listen to.
The generic midi versus funny experimental instrumentation play a part too.
Yeah it seems to me like a human bias against ignorance. We have this notion that if people that don't know the knowledge that we know they must be dumb because, "everybody knows ____".
Kids are literally just the definition of inexperienced.
And then Elmo happened and then Barney happened, and things have been on kind of a downhill slide into brightly colored, C-major MIDI music Cocomelon happyland.