Hmm, one particular area for end game. Would be open world. There are a lot more FFXIV players per server than FFXI had (naturally less MMO players at the time, FFXI had good numbers for it's time). You have that massive amount of players who engage in one zone, that wouldn't be conflicting at all or cause a lot of drama.
It isn't to discredit the idea of open world content, but it needs to make sense in the structure the game has built already. Like have Peiteskin treasure maps have a small chance of giving you an item that pops a more powerful NM in the open world and kill that to have it drop decent items/gear/tokens. Having a sky/sea like area causes more trouble than any good that would come from it. When you come up with an idea, you have to think about how it affects other content, server structure, and game fundamentals.
FFXI had a lot less players, especially in end game in comparison to FFXIV. Getting to 75 was a thing not many casual players of FFXI achieved till long down the road. In it's prime you saw 4-5 endgame LS's at most in Sky/Sea at a time. FFXIV works to get you to end game, meaning there would be much more lv.50's all gathering in one area and fighting each other to have room or claim mobs in an open world area, which causes conflict which I can tell you as a Sky/Sea raider since their release to 2010, no one liked dealing with the things you had to endure in there. I rather it be instanced where my FPS won't dip and my group can work at their own pace.
