“A few decades ago, before TV commercials became obsessively concerned with prostate problems, Jack Kerouac wrote a book called ‘On the Road.’ It was greeted rapturously by many as a burst of rollicking, joyous American energy. … ‘On the Road’ turned 50 last month, and over the past few weeks a line of critics have taken another look at the book, and this time their descriptions of it, whether they like it or not, are very different.”