Although I kind of like the bags (they would be great in my boat, for instance), I feel that if the vehicle is ever left anywhere, those things are an invitation to an opportunistic thief. I can see things like this being useful in ,say, the military etc. where a vehicle isn't just left somewhere unattended.
But if the vehicle is not left, I very much "dig" the practicality of them - especially those for the "hull sides" (i.e the camper sides).
Funny you should mention this. I've been thinking of making a bunch of modular storage pouches for the rear seat of my crew cab. Even thought of those velcro patches, to attach tags labeling what's inside. After thinking about it for a while, I realized it's like put up a sign that says "steal this stuff". I would still like the pouches, but I need to figure out a less enticing installation. Maybe I can cover them all with something, like a blanket that is the same color as the interior of the truck.