The real reason is that the crack wars of the 90s have ended.
Not "the" reason, but certainly a factor.
Since the 1980s, more middle class Black families left the South-Central (now South L.A.) section for other suburban communities. In 1970, Blacks made up 18% of the city’s population. According to the 2000 U.S. Census, African-Americans are 11% and some demographers expect the percentage will be cut in half to 6% in the next decade. Los Angeles’ Black community has been dramatically improved, though a Black underclass continues to reside in lower-income sections of the city.
-exactly—likewise Chicago and NYC—the rationalization of the drug trade into a peacful semi-monopoly has done wonders—