Couldn't you design the assemblies so the boards could be conformal coated with a dialectic layer and them potted with a RF absorbing layer and then a grounded layer as not be able to pick up the emissions in the first place.
I suppose you could, but it'd really ruin your reception. As long as you have the need for a functioning antenna connected to the device, stray signals will be received as well as transmitted. Not to mention that your idea would increase the build cost in a way that most manufacturers would deem "unnecessary".
My normal power consumption is about 400-500 kwH per month. Granted I do have a gas furnace and water heater. Of course during the summer, during the months when I am running two A/C units pretty much constantly, it does rise up to about 1700 kwH.
But anyways 500 kWH is not at all uncommon, and is not indicative of living "in a one-room shack with a single LED lightbulb and a Mac mini".
"Free markets select for winning solutions." -- Eric S. Raymond