But there’s another, more self-serving reason that a particular type of superannuated rocker likes to put out an album of standards. These songs—penned by Cole Porter, the Gershwins, Rodgers & Hart (or Hammerstein) to name just a few of their most famous composers—represent the sturdy foundation on which all popular music is based. If you’re a pop singer or songwriter concerned about your legacy, linking yourself to the great American songbook confers a kind of late-stage artisanal legitimacy onto your entire career. It shows that you, too, have always possessed a deep and sophisticated understanding of authentic songcraft. If you’re worried that the world may remember you primarily for wearing Spandex pants and snarling “Do Ya Think I’m Sexy?,” what better penance than to croon “Isn’t It Romantic?” in a rakish coat and tie, carried along by a lush string section?