I can think of several reasons. The foremost is probably the constant race-baiting utilized by large elements of our government that like most elements of it, work for large corporate interests.
A second is large segments of the Ferguson populace seem to be members of a group which although only approximately 15% of the population, commits about 80% of the violent crimes and takes no responsibility for it. Yea even to the point of blaming society and more specifically in that instance, the police themselves.
A third is the constant yammering of the MSM on the subject giving the bad elements a platform to spread their propaganda and lies.
I agree with this. Remember, those other mentioned ethnicities are not a "protected class". In the media's eyes racism can only be perpetrated on the Black community. So if a Korean were to be shot by a white cop it would likely get local air time for a few days maybe.