I have to go with Shuckins on this.
Animation in USA died in the 70s. One of the truly enjoyable ( albeit subtle, until you look for it ) features of animation was the orchestral background.
The cost of employing a full orchestra as background music made such productions cost-prohibitive after the late 60s.
Not to say that today's offerings are bad, per se. They simply do not come close to the artistic level as those of 40 years ago.
Yes, I like Adult swim and their wares ( Venture brothers, Family Guy ) and, as far as anime, Full Metal Alchemist and Ghost in the Shell are pretty darn entertaining.
But, to be honest, they don't compare to good old bugs bunny and William Shakesphere, Coyote and Road Runner, and Elmer Fudd. ( Kill da wabbit! ).