That same 40s/50s generation idolized Thomas Wolfe (1900-1938) and praised his works to the skies. Nowadays he's forgotten and unreadable and people wonder what the fuss was about. Sometimes an artist becomes so enshrined in one generation -- Orwell, Camus -- that the next generation can't resist taking a swipe at the cultural icon.
Among contemporary writers, maybe Jonathan Franzen or Salman Rushdie. Maybe Toni Morrison or Zadie Smith. There's a feeling that there has to be a writer to fill a certain niche. Say, modern American condition of society novelist or post-colonial magic realist. Once the niche is established, Franzen or Rushdie gets forced into it and their works are praised whether they deserve it or not.
Morrison, like Fitzgerald, fits the American Studies niche (what's America all about then?). Like Faulkner she combines that with difficulty: books that have to be taught before they can be read. And she has race and sex covered as well. Zadie Smith can be marvelously imaginative, but she has trouble finishing what she starts, that's to say, trouble getting her novels beyond the initial set-up to a meaningful conclusion.
I can’t remember the name of the author or the title of the book but the most overrated book I ever read was the one about the boy who ran away from home with his dog and lived in the woods for about a year. They made it into a TV movie I think or maybe it was a short-lived TV series. Anyway, I had to give up reading it about halfway through because the chapter that had the boy removing engorged ticks from the dog and them using them to catch fish in a pond just totally disgusted me.