Joseph Eckert says on the Digital Photography School blog;
The very first photographs were shot in black and white. Decades later, even after the advent of color, many photographers—especially those concerned with creating works of art—continued to shoot in black and white. The format remains popular even today: nearly every consumer-level digital camera has a black and white mode available (for outputting JPEGs directly from the camera in monochrome), and all digital darkroom editing suites have at least one (and usually multiple) means of changing a color photograph to black and white. Indeed, there are expensive plugins available for Photoshop that are entirely devoted to the process of converting a color shot into black and white, and there dozens of groups on Flickr and Picassa and 500px that are exclusive to black and white photography.
Why do black and white photographs continue to exercise this hold over the fancy of so many photographers (dabbling, amateur, and pro) when we have cameras and techniques at our disposal that can capture every color under the sun? We can produce photographs of spectacular color range, with arresting reds and blues and greens and yellows, and yet the simple power of an effective black and white shot can (arguably, of course) leave even the most brilliantly realized color shot in the artistic dust.