There is probably much history behind the concept of b/w being more artistic, in the sense that it came first, but I don't think that explains its allure. After all, most of us who are over ten have had the experience of working in both, and make our choices accordingly, more based upon horses for courses, I'd expect, than any artificial idea of one being more artistic a medium than the other.
When I find myself doing colour (on the computer) I often feel an urge to close the damn thing down and start scanning something old and taking it forward as b/w, regardless of whether the original was b/w or colour. Something about colour printing feels sort of, well, mired in the amateur ethic, part of a later snapshot culture rather than a more studied one of deliberate thought. Of course, this is only the case in amateur work (in its best sense) and has no bearing on professional work which is what it is required to be, and that's all there is to it.
There is something a bit boring about trying to match a transparency or produce something that looks sort of naturally coloured or toned; even worse (to me) is the effort wasted in distorting colour just to let something be different from what you saw through the lens. And that's the buzz of b/w: there is no reality that you might feel obliged to match; you go ahead and produce in a personal world of interpretation that has few rules - if any - and nobody can tell you your view is wrong. That's a kind of freedom, if you will. A freedom both to reduce a thing to its elements yet endow it with a power that it didn't obviously have in life. I like that.
However, I don't believe in exclusive rules about this: there are strong colour themes that would just be meaningless printed in b/w. Both are valid but perhaps b/w can offer more freedom of expression in that your print is what you want it to be, not to be prejudged by viewer experience, just like a definition of art itself might claim.