I had a theory the other night that the only reason they are locking Ishgard behind 2.55 story is because Ishgard wont be instanced. Whenever you went into the waking sands or the raising stones it was an instanced area for you. So you would only see NPCs you've ecountered in the story when you went in those areas. Ishgard is probably going to have characters walking around that probably are assumed dead at this point. And since Ishgard isn't instanced for each player everyone can see them.

If this theory is true I kinda wish they had just put those story npcs behind a instanced area in Ishgard, so that people could get to lvl 30 and try out the new jobs.