Maybe they finally realized that once Armageddon came, no significant construction project would be able to even start without "This System's TM " infastructure (power grid, transportation) or industry (mining, steel mills, microprocessor manufacturers, plastics makers, oil refineries, etc., etc., etc.).
The RBC may be able to build a Kingdom Hall over a few weekends, but I wonder how successful it would be at mining the ore, smelting, casting and machining all just to get a single drill bit. Or make the glass from sand to construct double-pane windows. Or refine crude oil to make plastics for the light switches, and on, and on, and on.
R_O
(I suppose instead of Jehovah covering the ground with Manna every morning, every JW could wake up to go out and collect construction equipment and building materials..."Look Mom, I found a table saw this morning!!! That's even better than the 20 lb box of finish nails I found yesterday!!!)