It does seem a bit wasteful, but companies producing ASICs are fighting for lower power consumption. I would expect future power consumption per GH/s to go down.
Watts/(GH/s) will go down because of ASICs, but that will make mining more lucrative and they will have to up the difficulty which raises Watts/(GH/s).
Not if it's just because we're building bitcoin-specific ASICs. It might help push technology, but it'll also pull brain-power that would otherwise have been focused elsewhere. It's hard to know what the counterfactual would actually look like.
The current price of a bitcoin is almost exactly equal to its energy cost, and that's not going to change because if the price was higher people would spend more energy, if lower people will cut back.