That depends a lot from what direction you look at GW stuff.
You look at the miniatures and you see a very comic look. Gear and weapons are large, so you can easily see them when you look at a miniature from distance. The colours in most photos of miniatures are also comic. They want to people use lots of color. Colorful means more paint, and have you seen the prices of their paints..;) Also colourfull is easier to paint good than black/dark/"grim".
You look at the drawings and you have a very grim and dark look. Some of the pictures are almost disturbing, specially considering that GW target kids as customers also.

So even Games Workshop has this everything for everyone setting a bit and why wouldnt they.. its business..

Mr. Digital is right in this regard, especially with current 7th Edition.

When I say Warhammer Online is like a cartoon, I don't just mean graphically, I mean in the feel of the setting as a whole. The Warhammer Online setting feels like a cartoon.

Based on the RPG and the novels, the Warhammer setting is supposed to be very dark. At the beginning of the first Gotrek and Felix novel, for instance, they charge into a Chaos orgy. The introduction in the RPG warns that the game is for mature audiences only. This is not how Warhammer Online is at all, and that's why I call it a cheap parody of Warhammer.