This question is tagged "history" so, some history --
Photographs (of course) don't have to be literal captures of a scene. Plenty of photographers (past and present) have manipulated the image to reflect their feelings about the subject (or other stuff).
Pre-digital (and really, before desktop computer image editing -- which pre-dates pure digital photography by a bit), making color prints in the darkroom was tedious and the number of variables you had to control for using a limited number of tools you had made artistic exploration difficult. But with traditional B&W film photography, you had a wide number of tools (colored filters on the lens to change contrast, different contrast papers and all of the other darkroom techniques) and a limited number of variables in printing -- the exposure and the contrast curve for your single "color channel" (gray).
Also, by removing the color -- which humans have a good memory for in terms of what looks "right" -- you have more freedom to move away from a literal capture of the scene.
For color, a lot of people ended up preferring slides instead of prints, but it can be difficult to hang a slide in an art gallery. So color became less important in the art world.
Post-digital, there really aren't any limitations on what can be done with a color image and people have done some amazing exploration with HDR images, manipulating different color channels independently in different ways, etc. All of which are important additions to the creative toolbox.
But there is a huge history of B&W imagery in western culture, so there are still people interested in it. And sometimes a self-imposed limitation can be part of the creative process (like folks who just post the JPG files straight off the camera, without any post processing).