Personally I think this game is increasingly stifled by the obsession that a portion of the community has with what I can only describe as a misguided push for 'purity' of the lore. Mysteriously this obsession never extends across the board. There's plenty of interviews where Yoshi-P has stated outright that the game isn't a matter of 'good' and 'evil' but merely different perspectives.

I don't think every last little thing added to the game needs an explanation for why it exists. PvP is a common feature in pretty much every MMO that I've played. Do I think the development team would bother adding open world PvP? Probably not - if only because PvP is arguably the most neglected part of FFXIV overall in the present day.

A specific area of the game world considered to be 'no man's land' where any and all can visit and fight each other for treasure, coin and glory would easily fit into the game's story, though. We've already seen constant quests where the player character moves to kill someone or something for no real reason beyond being given a five second sob story. Both in the case of humanoids and innocent animals minding their own business.