Some time ago, I went through a phase of painting faces in black and white gouache. It was a satisfying exercise. I suspect a tiny part of the black and white appeal was that I wasn't sure about painting faces in colour, especially watercolour, which is difficult to control especially when painting wet on wet. But there comes the moment when you just go for it and damn the consequences.
Simplicity is the removal of the useless and the unnecessary--source unknown