I disagree with you on this, Bjorke.  To me, that is like saying that analogue photography has an artistic role that a modern photographer is best to ignore.  Or that landscape photographers should only do digital color work, or they will invariably be Ansel Adams wanna-be's... you get the picture.  You should not invalidate a practice only because it was once mainstream, but nowadays ceased to be. 
I hope I don't come across agressive, or as a finger pointer (which would be ridiculous; I've seen some of your B&W work 

 ) , I'm just trying to make my point clear.
I personally shoot black and white documentary projects, and do so for a variety of reasons.  I think Jeanette (BWGirl) has a very good point on why B&W reportage has such an impact: It is shot with such an impact in mind.  Furthermore, it often emphasizes issues otherwise ignored or played down by society.  Such issues, when once again confronted, greet society with an open-handed slap to the face.  Or at least the photographer hopes so. 
By photographer I mean me. 
I hope I don't sound like a snob... (heck, I've never published any of my documentary stuff).
As for why B&W, to me it's simple.  Color, to me, is 
ugly.  It's confusing, arbitrary, and othewise pointless.  I really, 
really dislike color.  That is why I shoot black and white.  And that is why digital is so scary to me.  Digital, like color, is arbitrary.  B&W is less so.
The fact that black and white isolates the elements in the picture is considered in the above point.
As an interesting side mark, I tend to think that color work emphasizes the "moment" much more than B&W.  To me, color is to snapshots as B&W is to timelessness.  I usually think of B&W documetary work as stressing a general/universal issue, rather than a specific event.  Think Salgado's "Migrations" as opposed to whomever's  "Diplomat meets President".  This is an exageration, I know, but I think it makes the point clear.
And of course, here is the disclaimer:  I dig (some) color work as well.  There are people who do it well (but my mind just went blank). 
But to me, B&W is still king.