The Raptor is a strong truck, let's be honest about this. Ford screwed up advertising the damn thing though, thats obvious. It's limits were exaggerated. That said, not all of these bent frames happened because ford said the truck can do "this", and it couldn't. These trucks are being pushed, and pushed hard. Some of that is fords fault, some the crybaby owners who want to get 4 feet of air and land at 100+ mph and expect sh*t not to break.
Like TA said, all manufacturers make sh*t that's going to break. Some more then others...but still. I would blame the advertising campaign more then the engineers.