There are many extraneous doors in FFXIV. The devs put them in as placeholders for possible future content. That doesn't necessarily mean all of them will be used though. Sometimes it's better to be prepared. There's those gates in Central Thanalan and East Shroud that have sat vacant since 2.0 launch, as well as the door and hallway that leads into the Gelmorran ruins in North Shroud. There's also a slew of doors added to 3.0 maps.