That's just it, they have. In all the marketing/media that Ford put out on it, nowhere does it show it hitting a decent size kicker at a great enough speed to cause damage. All pics or vids are only of high speed on relatively tame terrain (aside from some moderate whoop sections or "bumps" and whatnot) and jumps that, well, have been at way lower heights and lower speeds than some have done on their own.
This is a design in the frame no matter the model or package of F150 and I'm sure that impact guidelines played a role. Could it be better? Yes. (the 04-08's did not have the hole there and used a bumpstop that bolted in from the bottom) It would've cost Ford a ton of time and money to modify a new crumple zone into an already designed frame. That's not cheaping out, it's just an area that they obviously did not encounter any issues with during testing........testing that ultimately determined it's capabilities......wich they then marketed and put into media. So should it bend in a severe enough impact, yes.....but that does not mean it should be warrantied due to people over doing it.
By the way, I was also a 19K