Companies generate dollars by first generating things that some people find useful. Just generating dollars by themselves should be done with the smallest possible amount of electricity.
Bitcoin's energy usage is proportional to its market value so you might say it always uses the smallest possible amount of energy (given the current valuation).
We have yet to see if alternative systems like proof-of-stake can gain the same trust and replace proof-of-work while actually consuming less energy in practice. I'm hopeful though.
Right, the creation of Bitcoins only redistributes the value. The value mining provides is actually in outcompeting potential attackers who might want to change the consensus of the network.