The point is not really why those planes go to ground and crash (pilot errors .. malfunction of some equipements .. etc ..) but instead what was the result when they make contact with the ground.
A good point, but the question is was it out of the ordinary. Though not an expert on these things I would imagine each and every design has its weak points. As long as its above the design criteria thats fine. Hence an airframe under circumstances that are roughly the same should react the same. This would depend on loading etc etc.
So the real question is how did the airframes hold up. And of course did Boeing mislead, I would think theres going to be a lot of Legal jargon etc that no one will agree on.