Yeah, but the whole point here is that the engines are very specifically designed to break off in a way that preserves the integrity of the wings.
The integrity of the wings is a function that supersedes just about every other possible thing on a plane. You can safely land without any engines. You can safely land without hydraulics. You can safely land without gear. Without wings, a plane is a brick.
Indeed. And maneuvering speed V_A is designed such that as long as you don't exceed it, you will stall before breaking the wings off in case of turbulence or full control deflection.
Nah, an engine getting ripped off will not tear off the wing since this is the level of force and flex they are designed to withstand: https://www.youtube.com/watch?v=--LTYRTKV_A
The engines are built to rip off cleanly, because when they don't, they have caused https://en.wikipedia.org/wiki/American_Airlines_Flight_191 and https://en.wikipedia.org/wiki/El_Al_Flight_1862 which were fairly serious and catastrophic accidents at least partially caused by the engines tearing off and damaging the wing in such a serious manner as to cause a stall and crash. The wings stayed on the aircraft in both instances. Interestingly, both accidents were caused by those same sheer pins being damaged in minor and unpredicted ways.
I highly doubt the wing is DESIGNED to cleanly separate. Planes are just very not rigid for something going such a high speed, and so tend to turn into confetti when faced with a harder surface, like a runway or a concrete building. Usually the only parts that survive serious crashes are the landing gear struts.
I can see a boat's hull be designed to crumble as safely as possible under a headson impact. But the situation is not the same. Boats usually stay in water at all times. An accident might put them under water. The situation is different with airplanes: all airplanes are guaranteed to eventually impact the ground, just ideally in a controlled manner.