I sure like heated seats in the car. They're almost a necessity with either vinyl or leather seats, because it takes forever to warm those with your butt. But I'm not as sure about cloth seats needing them. When I drive Mah Woman's car, which has unheated cloth seats, it's not uncomfortable even in pretty cold weather.
My airplane has cloth seats. I had Oregon Aero do their comfort conversion to my pilot seat, and although it's hard as a brick when I first get in when it's cold, it doesn't take too long for my butt to warm it enough that it becomes pliable, but in the meanwhile, it's really not all that cold feeling.
My airplane's heater is sufficient down to about +20F, and gets progressively less powerful as the temp drops from there. If I flew in colder weather than that, maybe heated seats would be a good idea. But I mostly don't like the cold all that much, so I'm not likely to fly in colder weather than that. With age comes wimpiness.

Cary