I don't know about you, but I can definetly see the point. I just spent all day cleaning out my tent, sleeping bag, and bike. It was filled with sand, salt and all sorts of other crap. Granted I have used it alot and was doing a bunch of partying the last time it was out but still it seems to me that having a tent up on the roof of the truck would minimise the dirt, sand, mud that got in it. Also it would also be a clean flat area to set it up and then you would just need to try and get the truck in a semi-flat area.
I think the ones that fold out as one piece make more sense but even a normal tent up top would be nice. It would be more modular to not have a solid mounted tent. I can see that going either way.
The more I think about it, the more this is the direction I think I am going with my truck. Its simple, wouldn't stand out, and still be easily used to haul crap when not camping. The catch for me is if I put a lumber rack up there, it would make it even more difficult to remove the cap to load quads/dirtbikes.
