Especially once complete independence from an electric utility is achieved.
I totally agree with you that the time to install this stuff is at time of construction. Unfortunately real estate developers don't really care about how much it costs to _operate_ a building, they only care about building it as cheaply as possible, and selling for as high a price as possible.
The cost to increase insulation, add solar and batteries, all electric appliances, would all pay for itself over a decade or so.
Most homes in the US are occupied for many decades (not all by the same owner) so the savings are substantial over the lifetime of the building.
Of course, the consumer's savings are the electric utilities losses, and we know who has the pull in policy creation...
