These headliners are historically bad.
Eminem played in 2011 and was ungood
Outkast is solid if you can't catch them at Forecastle or Milwaukeefest (or Coachella, or Governors Ball, or Firefly, or Voodoo, etc)
Kings of Leon are shit
Skrillex is 8th at Bonnaroo and third on his (weak) day at Coachella
Arctic Monkeys - fine band, questionable headliner, 9th at Bonnaroo
Calvin Fucking Harris - played a pre-HL set in 2012.
Even if you're REALLY into Eminem and radiorock or untz, that's just objectively bad and unimaginative. But most people here realize that.