It comes from the core belief that comfort requires resources. "Toughness" helped my grandparents through hard times and allowed vulnerable people to use more resources. There just wasn't enough to go around and giving up small comforts the good of others was seen as a manly thing to do.

Not that a heated seat means much if anything, if it's already installed, fair game use it. When buying a truck I could definitely think of a better place to put $750 then in the pockets of a big truck company just to be warmer 3 minutes quicker. Or choosing to use less energy heating a home when a sweater and blanket will do. Or buying reusable dishes and cutlery even though it's cheap and easy to throw away plastic.

There's a point for everything and forgoing comfort for a good cause shouldn't be made fun of. Even if it's become a manly meme of sorts.