I see what you mean. Maybe 2D art and 3D art should be combined?
I think 2D and 3D art are distinct enough to be considered their own things. Animations should not have their own section as animation would be a subset of 2D or 3D art.
Pixels, Polygons, Waveforms. :)
Edit: To add to my point, I wouldn't want 2D to be split into, say, pixel art, illustrations, and vectors. One 2D forum for all types of 2D art is fine. Same for 3D, we don't need low poly, stylized, and photo-realistic sub sections.