One of the worst things about mainstream journalism is the herd mentality. Sad to see it affecting the documentary world, too. Here we have a new film about Herb and Dorothy Vogel, the adorable, thoroughly middle-class couple who began collecting serious art in the 1960s. Persistence and charm paid off, and over the decades they amassed an astonishingly rich trove of now-invaluable art. But their story has been told, in newspapers, magazines, and on television. If you tell it again, tell it better. Don’t just retell it, with the usual clichés. This one, sadly, is just for bird lovers.