Reflective and transflactive LCDs are more common than, and long predate. E-ink monitors; I don't think they're as much an alternative as a default choice.

However, I see more e-ink compared to reflective LCDs, maybe I'm wrong, I think I've never seen any used by private users.

They're much dimmer than the surroundings because it relies on light through layers of polarizers and matte diffusers.

I’d guess they’re either significantly more expensive, significantly more power-hungry, or both.

As embedded displays yes, especially in e-readers, but as far as stand-alone monitors, or laptop monitors, e-ink is very rare, even moreso than reflective and transfoective.