The ability to have specific things hidden.

Being able to make the map change a specific way when certain conditions are met (like completion of a quest) to have the map change to reflect that. Say like a city is hidden by magic so it should not exist in the world until the magic is dispelled. Being able to have those changes built in the background would give creators a lot more options. In fact to add to that having Franz be able to swap out two different things when conditions are met would be great. Like a city being destroyed the world creator could be sure the structures that should remain standing are still there and things that should be destroyed are gone.