If you really want blatant commercialization, see Pokemon, Digimon, Yu Gi Oh etc. The latter at least had an interesting plot, and deeper characters. But both are basically cheap adaptations of Japanese anime -- draw a few frames with action lines, sell millions of trading cards.

Compare that to, say, Spiderman for FOX Kids in the 90s. Every scene was carefully animated and the plot was deep.

And to prove it's not just nostalgia, there were cheap shows back then too, like all the Power Rangers knockoffs. Anyone remember "Samurai Pizzacats"? Kind of funny, but mostly repetitive power rangers formula.

Even Japanese anime knockoffs were better before -- like Teenage Mutant Ninja Turtles.

There is still good stuff today but it's few and far between. I'm inclined to think the business objectives have changed more than the kids' tastes. It's like people used to play immersive 3d games, real time strategy games, and now so many play addictive pay-to-accelerate casual nonsense like Farmville or Boom Beach or whatever. Did people simply change their tastes to get ripped off? No, it was directed by business. Actual quality is secondary now.