Even the greatest books won't reach the audience numbers that can be affected by music. That's difficult to believe. American animosity towards Jews is mainly a religious issue. Attitudes towards Blacks are quite different due to the history of slavery in this country. Without the depredations of slavery, Blacks would probably be viewed in the same manner that Asians or Hispanics are today by the White majority.
Old habits die hard.
If you weren't a member of the group, you were somebody who was to be conquered, exploited, or just plain inferior. This doesn't even have to be a matter of race. If we were all one race, we'd still find a way to choose up sides. The fact that some groups of people have different skin colors just makes it easier to make those irrational choices. As another example, look at the tradition of using colors to identify armies, sports teams, gangs, etc.