I'm more concerned that it takes something "wasteful" like mining to make people wake up. What about DRM techniques like HDCP? Even with hardware acceleration we've been wasting power for at least a decade to encrypt every single video stream so that we can stop piracy. Piracy still exists. Mining most definitely uses more power than video encryption but only one of them has really produced anything of value.
Efficient? Maybe, you can still have inefficient hardware. The hardware dedicated to HDCP encryption is single purpose, just like a Bitcoin miner. I'd expect the Bitcoin hardware is far more tuned for efficiency than most hardware HDCP circuits since power usage is the major cost of owning a miner in the longterm.
I'm not aware of any actual metrics and like I originally said I'm pretty sure bitcoin mining still uses more energy.
Bitcoin (well, its descendants now) makes my international money transfers dirt cheap while DRM prevents me from using media that I paid for on my favorite devices.
