They represented a new reality in paintings that depict radically fragmented objects in multiple views. So in one blinding sweep, art as we know it changes - instead of making things look like they look, the artists took it to themselves to show things as they are, not how they look. By completely discarding the traditional forms, the artist was now free to use color, shape, form, line-thickness all towards the purpose of putting through a message. Cubism is an advance in many ways, not only did it fully shatter a paradigm of dimensions unimaginable, but it brought art closer to the individual. Not to say the Cubists weren't talented, they certainly were - but instead of having to be Michelangelo, a normal person could sketch together a picture and not feel like a fool because it didn't look exactly like the thing they were drawing.
Cubism is a wonderful tool, especially for preliminary sketches.
It is able to capture huge amounts of detail into so few strokes, similar to the Oriental technique - though it works on capturing the spirit not the form, but the harmony is there. The Cubistic paintings take the least amount of time due to their filtering of un-needed things, and as the artist doesn't have to punish themselves for messing up so many of the things associated with painting, thus it is much more relaxed and carefree.