All I’ve seen are a few pages of Red Star with CGI used for hardcore mechanical illustration, but the Man says such things exist.
The first problem is character design.
In illustration, the basic unit is the line. Lines suggest shapes and masses, but they can be manipulated — always — to suit their own aesthetic purpose. Notice the difference between real hand-drawn animation and the stiffness of toon shaded CGI. Toon shading is cute, but it’s nostalgia. If you want to draw, learn to draw.
In illustration, lines are easy, shading is hard; in computer graphics, it’s exactly the opposite. Learn to light, and the software takes care of shading. Edges — lines — are a byproduct. Models are models. You don’t draw in 3D: you sculpt. You build.
The basic unit of CGI characters is the mass, and that’s where you need to go to get personality. Character design in CGI is more than trying to fudge an illustration to life in 3D. What’s on what, near what, across what? How does it fit together? Solve those questions or you’ll never get beyond flat, lifeless Poser-porn.
And that’s only the first problem.