It's been discussed before in other places on the forum but miners are building more efficient BUT more powerful miners.
Every new generation of miners use less power to generate more hashes. BUT, they then cram in more chips to make each miner more powerful. Made up numbers but: If in the last generation you needed 100 chips at 10 watts each to generate X amount of hashes but in the newer generation you need 80 chips at 8 watts each to generate the same X amount of hashes you could in theory make a miner just as fast as the old one but that uses a lot less power because you would be using less chips that are more efficient.
But what they do is make a miner that is much faster then the old generation by putting more of the more efficient using even more power but then now generate X+50% hashes.
Great for big miners in big data centers where power and noise does not matter. And well, the small home / hobby miners are out of luck.
To put it bluntly, for now, WE ARE NOT THEIR TARGET CUSTOMERS. There are obvious exceptions, there are people here who are running larger farms and such, but are the exception.
Gone are the days of the R4 and things like it, for now anyway.
-Dave