Why black and white many may ask well check out my post at Scrapmatt's to see many more wonderful creations using this colour combination.
Tones of grey, whites and blacks, like a old film on the tv are expressive, they have a lot of emotion caught up in them. The can be dramatic, or romantic, packed with action, take your pick. After a while of accepting the art for the way that it is, you stop even noticing it's not in color, just as a good film draws you in black and white or not, good art will do the same.
Art can touch your soul, inspire you, and bring you to know things about your self you never knew before. If you look deep enough, you can see that in any art, because that's what art is for, that's what it is supposed to do is make the viewer feel something, anything. Once a piece of art has done this it has done it's job.
Now that is why I like black and whites so much, this is why I don't feel the need to put color into a lot my work. I know a lot of artists who feel this way as well. So whether you are looking into drawing black and white drawings or you are just trying to learn why artists don't always use color, I hope this has helped you and you found what you were looking for