Even if you don't believe in climate change, MWh is a useful metric. Electricity is not free. Drastically increasing demand for electricity drives up the price

Even if you don't believe in climate change, MWh is a useful metric. Electricity is not free. Drastically increasing demand for electricity drives up the prices for everyone, in the short term, as electricity rates go up. Even once more supply is created--not an easy thing--society as a whole still bears the risk that the Bitcoin-driven demand will go away (due, e.g., to a crash in value) leaving us with an oversupply of electricity. Either way, "Bitcoin uses more electricity than x" can be a helpful comparison to more effectively convey just what we are signing up for in adopting Bitcoin widely.