Actually im not doing outlines as much as I am doing this:
The facial/body lines, mouth, eyebrows. All that good stuff.
EDIT: Some of you may recongnise the style, it's inspired by Samurai Jack. I've been experimenting with using anim8or as a 2D/3D cartoon editor since 2004. Unorthidox use of the tools, but hey. It does work.
(These are mine, but they are not hosted by me.)http://www.youtube.com/watch?v=QJSNvEzhEC4
There's a bit of language there, mind your ears.
But basically yeah, thats the point of using the paths. Trying to augment the style i've been toying with for a few years. Clean it up. Using paths and filling them in, while it does work, as you can see it's not really a science, you can easily create shapes that you dont intend to. Using the paths would ensure the lines dont get thicker/thinner.