In China it caries great religious significance as well as believed to help recoup blood lost from our monthly friend, post surgery, and during illness. They are also only used in soups and stews that require little meat. In Singapore, it is for pre and post natal diets. The only thing proven is they have twice the antioxidant carnosine than regular birds, and the health benefits come from free ranging instead of battery cages. In my search there have been black chicken products everywhere but not much real information. Scientist in the US are researching them, when they finally figure it out I am sure the "fad" will die like everything else. China will however still use it because it is deep in their culture.
The difference being, in America they could never bear to kill their little silkie-kins, but in China they will actually kill them and eat them. That's one reason it will not catch on here in a big way...evidenced even by this thread...on the meat bird section.....where several people plead for the life of Mr. Silkie Pants but didn't mention once to stay execution on the big, ugly roosters in the pen.
We Americans are mush pots. China knows what it's like to be hungry and they are resourceful in their nutrition sources....dogs, bugs, etc.