Considering Eureka, Trust, Squadrons, soloing dungeons, the question about the server charge is a false problem. The wards are heavy only because of the personalized extoriors and gardens. Everything else is already instancied anyway : interiors of house, apartments, Inns, FC rooms.
And if you consider the technology (everything that is no-sql-like, in other word live-data/dynamic memory), we can ask the question about the technology of the game itself that starts to look dated.