I think the idea of a Go-bag is good if a hurricane is coming, etc. It has to be something that is on the forefront of your mind or you will forget you have this Go-bag! Naturally, there has to be an escape route and a destination.
As far as the Witnesses and their Go-bags: I had asked a JW a few years back just WHERE they are going to?? They shrugged their shoulders.
I assume it's all about just disaster preparedness, but I somehow got the hint some JWs are acting like they are going to the promised land.