A black and white image is more likely to be defined by lines and planes of contrasting tone. Tonal differences help to emphasise form and the relative importance of differently shaped elements in the composition. This requires an element of seeing in black and white as much for the viewer as for the photographer, and an awareness of shape that differs from our more casual reactions to colour.
Whether viewed as an art, as a craft, or as a subset of chemistry and physics, photography is an inclusive medium. It can be as much an art form as a sociological record, and can incorporate genre as easily as drama; though I would argue that the most meaningful work in say, photojournalism, is invariably underpinned by an understanding of painting and drawing, or music, or even theatre.