Tents were only used from up to FF9. I personally would like to see how in a MMO it would be applyed.

Whats a Tent...?

In past FF's Tent was a item that could heal all your party members in a Field Area or at a save point.

Few ideas...

/tent emote just for fun. Kinda like /sit.

Retainer Shop maybe in Field Zones.

Way to get Bed bonus when you log out in a Field Zone.