I think the main advantage of Karplus-Strong is that it is (or at least was) cheaper and more simple to implement, than to for example an algorithm generating a

I think the main advantage of Karplus-Strong is that it is (or at least was) cheaper and more simple to implement, than to for example an algorithm generating a similar sound additively from sine waves. AFAIR the original paper describes an implementation using an impulse, a simple circular delay buffer and an averaging (addition + single right shift) filter. Simple additive synthesis usually falls short for something like a piano, too, since there are a lot of factors that influence the frequency content of a single struck note. This was posted a while ago, describing Pianoteq's approach to piano modeling: https://www.pianoteq.com/tutorials?play=modelling https://www.pianoteq.com/tutorials?play=modelling