What is your assessment of how well American democratic politics and values served the dreams of diverse American peoples in the postwar era?

I would say that American democratic politics and values have served diverse people imperfectly.  This is sort of like the story of our country in general -- these people have not been served perfectly, but things are tending to improve over time.

Clearly, there are many "minority" groups who continue to have grievances even today.  People of color are generally poorer than whites.  The criminal justice system seems to be more punitive to them.  Gay people lack what they consider to be basic rights.  Even women continue to have what some consider to be problems in securing equality.

At the same time, however, things are so much better than they were at the end of WWII.  The democratic process has given rights to minorities and to women that were unthinkable in 1945.  This shows me, at least, that things are generally improving.