They just added world visit so you can play on all of the worlds on your datacenter. If you move your home world to a place where vacant houses are available, you won't be leaving your friends behind. Simply travel back using the main aetheryte at a city after purchasing a house on a different world.

Your friends can also use the visit system to travel to your world to see your house. At times when you want to chat to people who are not currently on the same world as you, the following work: /tell to friends, cross world linkshell, FC chat. Only normal linkshells do not work for cross world communication. They are working on increasing the amount of cross world linkshells we can join.

It takes more consideration than just copy pasting to increase the number of wards. There's a significant server cost running a large amount of wards simultaneously. If they generate too many wards they cannot guarantee adequate server performance. Certain datacenters may each be getting one new world soon which would add many thousands of new open plots to purchase (EU).