Like movies, videogames and other forms of popular media, cartoons fell prey to 'corporate panic'(TM) Today, most cartoons are produced directly by or under heavy supervision of a few corporations who view cartoon as very serious business. And they want to play it safe, what means minimizing the probability of failure of an aired show.
They reach that goal by conducting huge surveys to find the lowest common denominator, relying on concepts proved as succesfull, minimizing the cost for animations and dismissing concepts, characters and plots which bear any risk or any chance of being offending to anyone.
The logical consequence of this attitude is what we see now. Less shows, imitating older or recent succesful cartoons, carefully adjusted to a target audience, political correct and often lacking creativity, an interesting universe or characters or just hilarious madness.
Another blight is the now common use of computer generated graphics, often making the cartoons looking even more pretentious. i am aware that is is no longer possible to go back to traditional animation for cartoons produced to minimal costs, but this does not mean it has to look like sh*t!
Imagine shows like Ren & Stimpy or Rocco's modern life would not have been aired yet and you would have to try selling them to a tv station.
Would you succeed? Most probably not. After a look at the f*cked up characters, the strange aesthetics and the abstruse humour not only aired at 6 1/2-8 3/4 year olds you would be dismissed faster than you can say "Ragnarok of western animation"!
That does not mean there isn't any creativity left. I really love Spongebob(after the first few seasons when the grotesque found its place in the show) and respect the efforts of Avatar and Teen Titans in telling a meaningful story, but that's about it. Not much more in modern cartoons to amuse me apart from a few chuckles here and there.
Well, just my two cents.