I agree with you that it's a very unsignificant amount. BUT, mining is still very silly and non productive.
It produces bitcoins. And, it is necessary to process transactions in a manner which assures they are not corrupt. Next time you are at the stop light in your car, don't stomp on the accelerator. This will save more energy than if we all ran heavy miners in our house. Quit listening to green fools who can add.
I've never liked green fools, in fact I've hated them for as long as I remember. (Starting with Al'Gores 'hockey stick controversy' mumbo jumbo)
But, I still think that this market will adapt to efficiency, eventhough PoS just seems like an even worse replacement.