Mining for gold is also a net waste of energy, from the perspective that gold has nearly zero industrial uses outside of the monetary functions of gold.
In third-world countries thousands depend on their gold mining jobs to survive. Add the workers in the mining industries in industrialized countries that would be out of work, and we see that a lot of people's lives would be severely affected if gold mining was stopped.
Bernanke is wrong: gold is the ultimate money. 100% of central banks hold gold, in spite of Bernanke's brush-off. However gold does have weaknesses that bitcoin can thrive on.
I do understand your point, though. From a wider perspective, why do we need gold if we can use anything as a store of value? I think its because of trust. Gold is a substitute for trust in a dog-eat-dog world. The question is, can the networks (and the bitcoin block-chain itself) be trusted enough to include bitcoin on the list of trusted stores of wealth?