Just an observation, I'm not really sure if it carries much weight but there are plenty of grim and bloody manga and the Shonen titles certainly can get bloody and yet when I look at a lot of shonen promotional art and covers the heroes are often smiling and the art is quite colorful and inviting and showcasing lots of characters and the seriousness inside is often balanced with silliness. I was just looking at the latest DC solicitations and almost every one has some muscled up characters flexing and gritting their teeth or shouting angrily or scowling, usually in the process of throttling another character.
It's really funny. Just open up a bunch of cover images and then flip through the tabs:http://www.comicbookresources.com/?page=article&id=39637
And their Vertigo line often looks drabby too. I think they'd need more Why I Hate Saturns and stuff like that that actually demonstrates more emotional range and just looks like fun for adults, teens, or whoever. Maybe this Sandman series might do some of that.