I agree that heat pumps are not a solution to more range in extreme cold.
However, the vast majority of people do not deal with regular extreme cold.
People are much more likely to deal with a lot of cold, and occasional extreme cold, or a lot of what-I-used-to-call-cold, and some cold.
The normal patterns in temperate to cold climates is where a heat pump would help, because it'd raise the typical efficiency and range, lowering operating cost and increasing utility.
However, the question is, how much would the heat pump cost? Because the money could be spent on extra battery capacity. Extra battery capacity increases range when you don't need heat, and increases your fast charging rate.
To me, there is no single solution.
Resistive and capacity for hotter climates.
Heat pump for mild and cold climates.
Fuel heater for extremely cold climates (and I don't include my Central Maine climate in that, a heat pump would be a better balance). Longer term I would favor ethanol heating over diesel, since it's cleaner (with good heaters), we produce a ton of it and will always produce it, and we could do with saving the diesel for the hardest uses to replace.