Courts: the popular angle
I’d say that part of the obsession, outside of élite circles, is due to a combination of : a) An educational system that hammers into people’s heads the notion that The Constitution and the Supreme Court are the representatives and defenders, respectively, of all that is good and right in society; b) A general lack of understanding of the history of the Warren (and early Burger) courts. People look at the decisions of the day – Brown v. Bd. of Ed., Brandenburg v. Ohio, etc. etc. etc. – and not at the social context. The Warren court was operating in an atmosphere of mass popular upheaval, and followed – not led – the public’s demands for change. The difference between Plessy and Brown is not so much the court’s composition as the public mood – segregation was already highly unpopular, particularly in the north, by the time the Brown decision was issued. The free speech cases that actually created the free speech rights that people now falsely believe have been applied since 1776 were handed down in the face of an insurgent public that was going well beyond the long-established limits of its accepted sphere (spectators, not protagonists).