I'm a comedy guy, and for that I'd want nice, sharp, funny backgrounds like the ones in the old Viewmaster reels.
I wouldn't have much use for deliberately hazy backgrounds (above). Sure they make the foreground characters pop, but so what? They lose the context, the whole sense of the world the characters inhabit.
I'll come back to this in a minute.
Especially in comedy, the backgrounds and props are almost as important as the foreground figures. Comedy is about stupid people, and the stupid world they inhabit. You have to make a world like the one in the Viewmaster above, one that's fit for ignorant characters to live in.
Of course I'm not being fair to the Kung-Fu Panda people. They were trying to do a humorous adventure film, not a pure comedy, and some of their backgrounds weren't all that blurry. The public liked what they did, so maybe they know something I don't. What I do know is that this type of background wouldn't work in comedy. It's too real.
In the world of ignorance (above) mountains don't know how to look like mountains. The Sun doesn't know how to light people in a natural way...but it still looks beautiful and our characters are still delighted to live there.
Lighting is just as important as design. There's nothing natural about the light on these George Pal characters (above), but look how good they look. In 3D animated comedy you have to light for ignorance and what looks funny. You need a funny lighting man.