Although we see in colour, there is something about the absence of it that can make a photograph more striking.
I tend to shoot a lot more colour than black and white in my personal work, but it is a unique experience to load up some black and white film and consciously look at a scene in a different way. Especially on the street, when they're not working in your favour colours can distract what you're aiming to capture and show, so seeing things in simple black and white can be a liberating way to shoot.
