Another reason I would want to use a 3D model as a base for tracing is so I could get light and shadows perfect and make sure they stay perfect for every single character and frame of animation(since you could use the same lighting for all of them.)
This brings me to another thing I noticed, there is this energy wave that Chun li fires in Street fighter 3 and I could(can?) swear that it was done in 3D and then traced. It looks too damn good, and if it isn't...I'm even more impressed!
I hope they let me hotlink this, cause I don't feel like uploading it
Also check out this animation
specifically this frame
Is this one frame resampled or something? I mean I took a look at the colors and they aren't all over the place but maybe they resampled it within the palette they had. Anyway I've always thought this frame was weird.
Rotoscoping needs good animators and also decent actors to work. Quite a lot of the big budget Japanese animation studios use rotoscoping for in certain situations and they make it work. Lots of the old Disney stuff used rotoscoping and they made it work as well.
I agree it can work, if you edit the rotoscope to fit more into the snappier speed of animation. Animation is about exaggerating what is real and that is what makes it unique to live action.