Glad the original misconception is out of the way. Let's hope a mod changes the topic title.
"9" was actually running through my head when I read the initial question. That's a perfect example of what we need more of in american animation, only in serial form. I am not sayign what we have now is bad, but I am saying that american animation should have more genres than "kids comedy, Kids action, Adult comedy".
A lot of the american series people mentioned are, although good series, most of them are "toned down" from their comic source material to be kid-appropriate. Most mature, non-comedic american animation is in movies though, unfortunately.
I`d love a serious wolverine/Hulk/Thor/Marvel series done like the "Hulk vs." movie, only on TV. It's strange that for marvel to make a serious series using their charachters, they had to go to anime. That's not a slam against american animation, but I actually think it's sad, in a way, that an originally american comic book series, even after all these years, still isn`t allowed to be made mature(and by mature I mean not for kids, but for teens/adults)/non-comedy american animation in series form.