It doesn't need to be for the whole house, it just needs to be for the lighting fixtures. Obviously nobody is going to use a microwave or blender on 12V. It's not like our bulbs plug into NEMA 5-15 outlets. Having good DC standard voltages and plugs would be incredibly useful. Don't bother running 12V everywhere, but like after the 120V light switch go to a single controller that then drives the lights for that room. Or have that be in the box with the switch, although that might still have the same kind of cramped heat issue.

And it's not like we need to just stop producing Edison socket styles tomorrow. But let's make sane standards today.