Big yay! I love B&W comics. I'd say maybe they don't grab as much attention in the webcomic medium, but in general I really like the look of Nate Powell, Jeff Lemire, Wes Craig, etc. I'm not much of a color person so it's really aesthetically pleasing to me when the inks are the main focus. Also I really like the hard-boiled art style like in Charles Burns stuff:
Contrast.... to the max.
And on the topic of horror, I do think that adding color to a gritty, serious comic might make it seem more... campy? Distracting? At least to me. It's like if Walking Dead were in full color. It'd draw in more readers, maybe, but it definitely wouldn't have the same effect in my opinion.