I guess it depends how often you need to use the bed. If you have to truck around that thing all the time just for those few occasions every year when you need to move large or heavy items you might be better off just renting a van for the day.

People should just do the math and decide for their own particular case if hauling around a huge vehicle with all the disadvantages that come with it (maneuverability, fuel consumption, parking, etc.) actually pays off when they need the capacity, or if they're better off always using the right tool for the job (regular car for most of the needs, rent big one for the rest). YMMV.