I do not believe that the "sameness" of the suburbs was an improvement on the "ethnic enclaves" of the prewar period. Instead, this lead to a stifling feeling and to greater division between people from different ethnicities.
Before the war, all kinds of people lived in cities. This, however, did not mean that all kinds of people lived together. In fact, people were very divided, as "ethnic enclaves" meant that people from the same ethnicity often lived in the same areas. However, there was still a level of interaction among different groups that could not be avoided.
However, when the suburbs were developed, it was mostly white people who moved to these areas. This led to a feeling of "sameness" as these communities were mostly made up of young, white, middle class families. This led to an even larger separation among different kinds of people, as minorities were left in cities, and white people were prevented of interacting with them.