In short, the go-bag idea as promoted within JW Land is ridiculous and illogical.
Assessment: The WTBTS comes up with things like this and applies a "one-size fits all" approach because they have little of value or interest to share with current JW members. If those in hurricane zones might benefit from a go-bag, then everyone needs a go-bag! Go-bag hysteria has replaced predictions like 1975, the selection of all 144,000 by 1935 and the generations predictions. Since WTBTS has largely abandoned or given up on making specific predictions they have to replace it with things like go-bags, volunteering for disaster relief and watching an ever increasing amount of JW produced streaming content.
As Sir82 mentions, the go bag "need" was a result of U.S. hurricane evacuations that caused mayhem for millions of people on the southern U.S. coast during the last 20 years. For anyone that might have to evacuate with at least some notice - the idea is valid and a smart thing to have some basic items ready to go. For hurricane evacuations this is likely something that makes a great deal of sense.
For 80-90% of the rest of the world, the idea that you will be able to grab your go-bag...get in the car...and just leave with what will fit in even a large hiking backpack is ridiculous. Also, many disasters are not evacuation events...meaning you are likely not evacuating to another part of the region or country. How many people do you know that have had to evacuate on short notice and that having a go-bag would have made it possible? I don't know anyone.