It raises a very simple question. What purpose do these large properties around the world serve? The printing and distribution of literature. This is the main purpose and mission of the organization. It is the continuance of a tradition that started with C.T. Russell. Publishing literature was the sole reason as to why the WTBTS was founded in the first place.
I would have to say that after a century of publishing literature; a membership of six and a half million is paltry. How effective is this publishing and distribution model? Not very much. Think about what could be accomplished if that real estate wealth had been used to utilize television, radio, and internet witnessing. If this is the most important message in all of human history, why aren't more effective methods such as these being used? Because that does not fit into the organization's traditional model: door-to-door distribution of literature.
Ray Franz noted that this tradition of printing and distributing literature has become the the benchmark by which the Governing Body measures success. The more printing; the better. The output of literature has been the standard which measures God's blessing on the organization. It is a badge of merit.
You see, most religionists are impressed and moved by what is appealing the eyes; whether it be large ornate temples, huge cathedrals, or the visual presence of the Vatican. Jehovah's Witnesses are no different. They are impressed and wooed by large printing operations and shipping depots. They are moved by large sprawling branch complexes which house the people who operate the printing equipment.
These real estate holdings serve more of a psychological need than a pragmatic one. Just ask yourself one question: if Jesus really did not appoint the Watchtower organization as his eartlhy agent in 1919; what does it mean for all of these billions of dollars worth of printeries and warehouses?