> I believe that is not because product designer don't want to change but some part of the supply chain / operation don't want to waste money on new design so quickly.

This was the root of several problems with that era of MBP. Intel wasn’t able to make good on their promise of new efficient CPUs, instead serving up reheated 14nm for the Nth time, and then Apple was stuck with a pile of chassises, heatsinks, etc (and associated tooling) that were incapable of handling the heat output of the CPUs they actually got.