Half Time Shows: Where are the Good Acts?

I don't get the selection process for the halftime show during the Super Bowl. Most people over 35 could not sing along with a Maroon 5 or Big Boi song. Why not get some iconic figures like Bruce Springsteen or Elton John etc? They have broad appeal and are known throughout the world. Even the ads are geared for most adults over 30. This halftime show was mediocre at best.