The purpose of that engineering feature is to ensure the wings stay on.
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.
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.