The semiconductor industry is also very happy to do hard things for marginal gains. They've spent a decade swapping out semiconductor junction materials at enormous expense because there's no other option.

The idea that reducing power consumption is also not large enough to matter is...yeah, detached from reality. Thermal density has been an enormous problem with increasing CPU feature densities. CPUs already run hotter then a kitchen hot-plate, which is why so much effort has been put into dynamic throttling and other tricks - you straight up can't run CPU circuit elements full-power for very long without the risk of frying them, or requiring a cooling system which is impractical for widespread deployment.