In my opinion, what gives them such a punch -- mainly, that is, aside from the literary craftsmanship aspect that makes them so readable -- is the fact that he knows himself well, and is more open and honest about it than many of us are.
That said, I have a hard time sharing his (somewhat qualified in the last paragraph) disappointment about what he deems too slow a political reaction of the U.S. working people to a long two-decade series of woes. The problem, I think, is the two standards against which he implicitly judges the evolution of the U.S. working people.
I say "implicitly," because every now and then he takes an explicit critical distance from them. But deep down, he doesn't quite get them out of his mind. One is the historical precedent of inter-war working-class militancy in the U.S. And the other is the set of off-the-wall expectations of the radical sectarian left re. the kind of political life that working people in motion are supposed to display.
I don't claim Carrol's forecasting accuracy, but I believe that the kind of political awakening that the U.S. working people (broadly understood) is experiencing/will experience will defy our stereotypes.
I can't quite put the finger in it, but my claim to "wisdom" here is my being an outsider to this culture.