This is because painting and other two dimensional works of art have long been the most significant mirror of the cultural mindset.
All art is simply a visual language that transcends literacy and speaks directly to the heart's eye.
Two dimensional work is the most easily produced, immediate and pervasive of all artforms. Sculpture is an interactive medium, always concealing some of its facets while revealing others. It requires the viewer to move around it in order to see it fully. A good piece of sculpture, whatever its style or size, works well from any viewing angle. It reveals it's ideas by means of mass, form and proportion.