What makes cubism special?

Answer 1

Cubism was a huge turning point in the history of art. Beginning with the Impressionists, the objective of artists began to shift from capturing detailed images of "a window onto the world." Paul Cezanne can be considered the founder of Cubism since his works broke down an image into it's basic geometric shapes and forms. Pablo Picasso and Georges Braque, two major artists of Cubism, were able to capture a 3D view of an image, which was revolutionary since all "traditional" art before this time period were flat and 2D. They were able to do this by breaking down an image into geometric forms and rearranging them.

Answer 2

Because it introduced a radically different way of seeing and rendering a subject.