PvP was in FFXI. It was called Ballista. It didn't have a lot of success BUT it was PvP.

As for PvP in ARR, I don't really care if it is present or not. If the equipements are PvP-exclusive with PvP-only boosts on them and it doesn't interfere with the PvE and PvE content... I don't mind. Let the people wanting to kill each other do so while I clear Behemoth's Maze, the Crystal Tower and do some multi-party big event against amazing foes (something like Dynamis, Besieged or Campaigns in FFXI).