Colors adds more value to the picture. it may be a light which enhances the color or some dominant color contrast or color creates some mood. Color is so natural and our world is full of colors.
Colors have strong meaning and emotions associated with them. http://www.color-wheel-pro.com/color-meaning.html
For example, if Red or Yellow or Blue plays major role in the scene, better to keep it in color itself. It adds more value to picture and visually enhances the picture.
I do follow some of the masters works for color inspiration.
David Alan Harvey
Few of my pictures in Colors.