This is exactly the issue. To deliver the power needed at such low voltage, you need thick cables. And thick cables are expensive in materials and installatio

This is exactly the issue. To deliver the power needed at such low voltage, you need thick cables. And thick cables are expensive in materials and installation. Can you imagine a typical j-box or load center with, say, a dozen of these bad boys coming in and leaving? Due to the size, the changes needed would not be confined to the electrical system -- you'd have to figure out a way to maintain structural strength and fire safety despite the large openings for cables. It's possible to imagine houses wired with low-power DC and high-power AC (both), but it'll never happen in my lifetime, hence a general lack of enthusiasm.