You raise some good issues and will be speaking out of school since I know little about building materials.

I agree that building materials are really more about cheapness, availability, and ease of construction than any other consideration. The common argument is that those older construction methods would simply be too expensive to be practical.

One thing I do know is that anything less than 4 stories tall can be made of wood and larger is steel and concrete.

You are correct, by increasing the voltage you lower current and can keep copper thinner. That itself is on the low end of the issues with the standards (even though a lot of the standards do represent legitimate guidelines for safety, I was referring more to the current trends).

The way those trends are going, HVAC will start to not be feasible in about 10-15 years.... at a point you can't squeeze more energy out of a system than is put into it.

This ties to the concept of the educated idiots.