All the "go bag" stuff happened after Hurricane Katrina.
Thousands, probably tens of thousands, of JWs were forced to evacuate their homes, sometimes ending up hundreds of miles away. There was no organized system of checking up on anyone, so it was the perfect opportunity for JWs to "fade".
The organization was, and is, utterly horrified that they might be forced to loosen even slightly their stranglehold grip on control & power over their adherents, so now there are orders for every congregation to have a "disaster plan", including giving your phone numbers and out-of-state contacts to the elders. So in case there is another Katrina-scale disaster, the elders can hunt you down. No more easy fading.
The "go bags" are part of the protocol for those congregation disaster plans. But as noted, by far the most important piece of that plan, from the WTS perspective, is making sure that contact information for every publisher is up-to-the-minute current and in the hands of the BOE.