I think the manufacturers often offer black as a subdued alternative to their flashier color-of-the-year. For example, Surly usually offers their frames in a custom color that may not be to many people's liking, so they also offer a "neutral" black color option on most (all?) of their frames. They probably wouldn't sell as many bikes if they offered them in "hospital foam green" and nothing else. Color is a factor for many buyers, so manufacturers would probably lose sales if they didn't offer a color choice, and the old "black goes with everything" adage still applies.

I feel the same way. I don't like the black-on-black look. I need some chrome components on there. That said, one of my bikes is pretty blacked-out because it is my lockup bike. I'm hoping that thieving eyes won't notice it as much. So far, so good.