You're thinking from the perspective of the miners. From the perspective of the hardware manufacturers that's an advantage. If you're making the hardware and y

You're thinking from the perspective of the miners. From the perspective of the hardware manufacturers that's an advantage. If you're making the hardware and you come up with a 10% energy savings, everyone must now replace their old hardware or be left in the dust. Hardware manufacturers will make a killing. The prisoner's dilemma you are thinking of only applies to the miners, it's a benefit for the parties selling them the hardware.