At one point in my life, I went through a stage of only wearing black and white. It wasn't a conscious decision, but it was just so easy.
1 - "Black and white" is hard to mess up...actually almost impossible.
2 - "Black and white" goes with everything.
3 - Black and white are easily the chicest colors. (Well, technically they are non-color and all-color, respectively. That's probably why they go with everything.)