The bottom line for any cartoon is that it boils down to one flattened layer of pixels being displayed across a screen. The software used to create it differs on ease of use and aesthetics. I find it much easier to manipulate humanoid action via Poser than any other program I've used (including Flash, Director & After Affects). 3D programs also make it easier for me to determine what point of view I want to use to depict the scene - and even move that point of view (camera) during the scene should it add to the storytelling. I'd rather use an easier method of creation - and if I can get my output to look like the aesthetics of 2D then that's a bonus when I want that aesthetic.

Before they made me they broke the mold!
http://home.roadrunner.com/~kflach/