Because flat things are easier to store.
Critical skill is unimportant or even annoying when openness and transparency are expected.
Graphic arts represent a meeting point between word and image, and now you want to find this mysterious point because you dont see what is so hard about defining what art is.
Fine art is not considered graphic design until typography is applied. The most accepted interpretation of the function of whimsical visual meanings is that they are involved in graphic understanding.