Well, the thing is that everyone is probably going to think "his" generation of cartoons and entertainment was the best. As we get older we progressively tend to think of children's entertainment as banal, which is probably what our parents thought of our stuff. Whatever stuff is on now, is probably going to be the epitome of bad for most.
*THAT* said, I was born in 1975, and turned 15 in 1990s. This means I grew up during the 1980s with cartoons like "The Thundercats", "Silverhawks", "He-Man and The Masters Of The Universe", "The Transformers", "GI-Joe" and others. This generation of cartoons was mostly super-hero/fantasy type stuff that while pretty banal, presented characters that looked sort of like people, and a lot of action. It sparked a lot of parental criticism, and you saw articles about how people would sit down and watch cartoons and talk about how many instances of violence there were in them per minute, as well as the lack of educational content which lead to the much mocked "Knowing is half the battle" and their segements and their ilk. The fact that a lot of these cartoons were also glorified toy commercials did not help things either from an adult perspective.
It seems to me that this lead to a lot more attention being paid to children's programming, an it was actually dumbed down to the point where adults felt it was like what children SHOULD be watching. A lot of the shows people remember fondly for being exceptions (that came about after my time mostly) were ones that specifically pushed the envelope, and also got in trouble for it. I'll also say that a lot of the surrealistic artwork that they used for things like "Ren and Stimpy" and the like never really appealed to me. Though I suppose this is a matter of opinion, I know a lot of people hate the way anime is stylized the same way, even though it doesn't especially bother me.
To some extent it seemed like cartoons based on well known super-heroes were given something of a pass when it came to the standards being enforced. Spider-Man, X-men, etc... pulled off things that other shows couldn't get away with, and were on a lot of levels similar to what you would have seen in the 1980s (perhaps even pushing a bit further). However it seems that the same "concerned parents groups" caught on to that, and things have gotten a lot more banal even in that context.
I think a lot of it comes down to an adult perception of what children should be like, and what they are actually like, and want, and it causes things to rotate back and forth as something decent is created that is popular, someone freaks out, and then we see a dozen lobotimized shows show up for a while, followed by another brief decent period.
Oh... and I could not stand "The Grim Adventures Of Billy and Mandy". The premise was actually cute, but the artwork was horrible IMO, and I thought every gag they had was pretty predictable (or dumb). Some would say that's the point, but well... tastes vary.
But then again there I go... I'm another one who things the cartoons of my day were the best, and that "Thundercats" was probably the greatest children's cartoon that will ever be.
