I note that you didn't answer the question. Every other camera is not black, some are grey, some have brown accents, and so on.
While I understand that the H3DII is almost certainly the best digital 645 camera ever built in almost every way, Hasselblad seems to have forgotten how to stroke photographer's egos. In a fact-based world, this is not serious, but a lot of the passion for Hasselblad is not there any more. People get excited about the excellence of the results, but not about the camera itself. The viewfinder, yes, but not the shell. I think Hasselblad needs to re-learn this. If you pick up a V camera, and then you pick up the H, there isn't the same feeling.
Marc (fotografz) showed how handsome the camera's basic shape is when he posted photos of his "black" H in the getdpi forums. The two-tone brown really is a nasty choice. I do have to admit to really liking the little H symbols in the rubber on the focusing ring of the lenses though. Clearly someone still gets it. You can build the best camera, or you can build a legend. The V camera was a legend. The H not so much. It is just a good tool.
Didn't I answer the question? There is no legal prevention on a black H camera as far as I am aware.
I also think in todays economy there is less room for legends and more of a need for tools that do the job.
We are also lucky though that many semi-professionals and amateurs choose to buy Hasselblads, that we are very grateful for and still cater for this market with occasional bespoke pieces.