Energy is so cheap it's not really worth the effort (economically).

And if it would be more expensive stuff like cooking or washing clothes would still hurt more than downloading a file with a big PC.

It is cheap until it is not. Cost of energy is dependent on where in the world you live, how it is sourced, time of the year, and if there is a natural disaster. Some places in the world, like parts of rural India, only have access to solar.

Expect energy cost to also go up in the USA with the administration pushing to phase out renewable energy with fossil fuels. Fossil fuel never goes down in value. They may seem to go up and down but over time always increase.

As we keep adding more and more computers to the grid it will require more and more energy.

Second hand computers with this energy efficiency will benefit the poor and counties where energy is still a costly commodity. I don't mind paying the initial cost.

Energy is cheap in some places of the world. Something that saves me, say, 50Wh, nets me 150€ at the end of a year. "Don't make things more optimised because my electricity is cheap" would keep us all stuck with big energy bills.