By doing PoW as a side effect of something you need to do anyway for other reason, you actually make mining less profitable for other miners, which is helping to eliminate waste.

This is an aspect that a lot of PoW haters miss. While PoW is a waste, there are long term economic incentives to minimize it to either being a side-effect of something actually useful, or using energy that would go to waste anyway, making it's overall effect gravitate toward neutral.

Unfortunately such a second order effects are hard to explain to most people.