The idea is to show that black and white are the supreme colors and should not be ignored just because people are used to them. There are some good reasons black and white are used all over the world. They contrast each other perfectly and when used in the right way can communicate any message.
The best example is the fact that books and most websites contain black text on a white background.
It would be terribly hard if any other two colors were used to even read. People can also use
white text on a black background but for some reason it's just not as common to see.
Also, since I love the simplest geometric shapes, I use black and white to draw them often.
I also have a series called rainbow geometry which uses a lot of other colors. I like to show that I can use other colors and that black and white are my preference not because I'm limited to them but because I really like them.