"Soon" is necessary to keep the field service and meeting attendance fervor going.
Who's going to put in extra hours if the end is more than a decade or two away, let alone more than 100 years?
Given the organization's overuse of "soon," I marvel at how many JWs are sure the end is imminent whenever there's an earthquake or war or threat of war somewhere.
It's one thing to get fooled into buying the Brooklyn Bridge.
It's something else again to buy it a dozen times.