People are reluctant to install them because they don't work as well as the good old boilers we'd be replacing. I'm not saying they can't, and I'm not saying that there are zero models out there that work. But in practice, a lot of us that have interacted with heat pumps have the specific experience that they get anemic as the temperature goes down and eventually become unable to do much of anything. I live in the mi…
Heat pumps work, but they aren't nearly as _pleasant_. You can write essays about the efficiency of heat pumps, how lukewarm air works just fine to warm the house, how heat pumps are great _most of the time_ and you can supplement with space heaters or whatever when they fall short... But as long as furnaces are accessible and affordable, an awful lot of people are going to choose to have nice warm heat that is always going to be nice and warm regardless of the outside temperature.