Recognising the cost and quantifying it doesn't need to target the BTC users. It can target regulators for example. If we don't keep bringing the issue up, does the issue exist? Should we also stop taking about climate change since we won't change the minds of people running coal mines?

Even without a call to action, changing overall sentiment can influence action in the future.

> Does anyone have an amount of power consumption reduction that they think would make Bitcoin use justified for the functionality it provides?

Close to 100%, given PoS coins exist. Especially once ETH and other larger communities migrate.