Forget about the ole wifs tale of engines designed to fall off and save the wing.
The engines are designed and demonstrated to stay attached up to and including the worst fan blade failure. The wing critical structure (fuel box structures, spar beams etc.) are designed to sustain a specfic gust load. and turbulence. If you take the aircraft outside these specified envelops and margins than things begin to fail according to design margins.
A good designer will obviously not attempt to design the wing as the weakest link, thus engines are noted to fall off more often than wings when overloading occurs.
The experience with the b737-200 was not a gust or engine overload, it was a mechanic foud up followed by metal fatigue.
The two crashed B747 was also a fatigue problem and not an overload problem.
The two mountain wave problems were an overload problem which the wing but not the pylon survived. (sounds like an adequate design to me)