I agree a little, but disagree on some parts.
First off, there's a little something called "Adult Swim", perhaps you have heard of it? There are also other cartoons that are geared towards adults and/or teens. Even some of the shows on Nickelodeon, the most popular cartoon channel for kids, shows the occasional joke to keep people with brains occupied.
On the other hand, there's the shows that are just too damn boring and made for 2 year olds to even be put on telivision. I remember going through the channels one day with my dad and all the sudden my dad stops at Tillytubies. I wondered why he stopped, so I looked up, What I saw scared the crap out of me. These Tillytubby things were giving baths to each other. WHAT THE HELL.
Anyway, the world of cartoons is a horrible place.