Its easy to assume that there is no longer tension between the different ethnic groups and polarized cultures that live together in America today, which in turn California is among the most diverse places to be in the United States.
The question is: is the situation any better between the "tribes" if you will, than it was at the time of MLK jr?
The institution of de jure segregation is no more in 2010, but what then is the cause of de facto segregation that is with us to this day? If the government is no longer imposing segregation, then why do we still have it two generations after the fact? Why do new immigrants live in neighborhoods of their own nationality here in America, even if they have more than enough money to choose to live where they want in America? The real question is: why isn't integration a natural process?
What causes Fresno California to be a naturally segregated city when European-American make a small portion of the population? Why do Asians not want to live with those of African descent, Mexicans in Fresno not to live in the same area as neither. Why do Middle-Eastern Fresnans live in a separate part of town as well? Why isn't integration easy to do?
While growing up in a mostly mestizo-Mexican neighborhood in southern California, I have noticed these natural inclinations as much as you might have too if you have lived in a neighborhood where you were a minority, or there were more than two ethnicities, and when tension is there even if so subtle. These subtleties that some call institutional racism are simple natural instinct, after all, one does not need to learn such "institutions" to develop the same result.
The natural instinct behind white flight for the majority of European-Americans is the same reason which keep other tribes together in the United States, and segregated from others. Even those who are of mixed descent pick a side (culture) sub-consciously, even if they are not wanted by the tribe they choose. These choices are what keep the variety alive, not integration which kills variety, the same as mixing all colors on a palette; until they no longer exist.
In the meantime try not to judge those who make such choices, because you and everyone around you has already made a choice of their own.