Yes, when they were deprived access to the voting booth, to civil courts, and the legal ability to engage in trade with the white majority, they would have been fully justified in resorting to violence. It would have been quite ugly, and something from which the nation never would have recovered - all so a bunch of white trash could feel superior to blacks.
Maybe so, but a lot of that desire to set oneself above others, be the "in-group," "us vs. them," etc. that you're describing is part of human nature, and not likely to be extinguished by a few laws the government passes. And it's not limited to whites, either. Don't forget that there are "Afrocentric" school curricula that perform the same psychic (as in mental-makeup, not "Miss Cleo") function for the black community.