I was thinking more like, that by stabilizing the rear with a beam the front corners wouldn't need anything because the force would never be transferred there. No doubt the main reason they don't do that is cost, but a close second is probably that they'd have to assemble the truck with that tailgate in mind. It's much easier to make them all the same, and just add the brackets when they add the MFT. This "universal" design is why you can add features from other trims to those that don't have it by tying in to existing connectors and/or mounting points. I've done that with cab lights more than once. I didn't wire mine that way this time because I think they have hijacked the fuse box with the computer now, but even 1500's up till the DS had the pigtail in the passenger side A-pillar for cab lights. You could install you lights, and plug into the harness and you had a factory install. I'm not sure if that's possible with the DT because you'd probably have to have them "activated" which is crap. Instead I just tapped into the parking lights.
Again, I'm on a tangent. Good point about someone putting all their body weight on the door though. You do have to design things with the thought of people doing unexpected stuff to them. I don't know why anyone would do such a thing (hang on the tailgate door), but I can certainly see someone doing it.
