#1. I didn't say judge, I said compare. You can judge based on perceived quality all you want, but comparing things based on that metric is meaningless to anyone but yourself. The whole point here is that you can't measure artistic quality. The only way to factually compare two things is by attributes which can be measured, and by measurable attributes TV cartoons have been the same for a very long time.
#2. Looney Tunes are not TV cartoons. Apples and oranges and all that.
Cartoons don't bring you the same level of entertainment value they once did because your opinions changed, and cartoons did nothing to change them. I like Rocko better than any current cartoon, but that's just, like, my opinion, man. It's not evidence of a fundamental change in the way cartoons are made, or a reflection on society or anything so profound. It just means I grew up and got nostalgic and I don't look at cartoons the same way.
I get a sense of snobbery from your post. Like, your opinion is worth something because you're an "actual comic fan", or that looking down on Adventure Time makes you more sophisticated. Hating stuff doesn't make you better than other people, and other people aren't worthy of derision because they
like what you don't like. De gustibus non est disputandum. Or in the words of noted philosopher Patrick Star: "Take it easy, it's just a drawing."
YOU HOLD YOUR FILTHY TONGUE!