I think a good thing to pull from XI atm would be a city hub (Jeuno), and an emphasis on more open world content (not instances) - increasing social interaction between server players.

Duty Finder is needed - as is great - to keep players connected across data centers, but I think that considering the game's life since 2.0, the open world has not 'advanced' - it has not been made dangerous or 'exploratory' enough like the world of Vanadiel. And that I think is something this game could use. I'm fine with there being 'too much' emphasis on instances, but not there being 'all emphasis' on instances - which is more or less what we have had since 2.0, that dynamic remains unchanged.