Electric heat is probably most popular where people don't use it much or maybe where it is the only choice.
I get that much, but I still suppose it'd be easier (in principle) to just install the necessary wiring and outlets for portable heaters of the required power. In my own home I basically have enough
already, at least when the other short-duration heavy loads aren't on; out of interest I previously stepped up to using
two 2400W fan heaters on separate circuits, which made the house warm enough that I actually had to take my
shirt off.
And yes, heat pumps
for heating only really work favorably in a rather narrow set of circumstances.
(Here's an interesting side-effect of heat distribution: When distributed
evenly as I get with my fan heater, my body-temperature self-regulates much better so I sweat
a lot less than when the heat is chaotically distributed, as I get from the air conditioners on reverse cycle. Which suggests that using the reverse-cycle could even end up as
false economy in certain places; you may save a bit of electricity on the
room heating itself, but those savings could easily be wiped-out by having to bath/shower more often. This is especially likely where the water heater
itself uses a resistance element; my own is a combination solar-thermal unit with resistance booster.)
