Like Miss A I find them too hot for me.
But I'm a knitter so I make them for family....whether they want them or not 
I started making them years ago for the children when they were small, then as they out grew the idea, and they became less fashionable so I stopped for a while.
Some times I make vest/tank tops with no sleeves as that makes them cooler.
I love the fact that they are fixing their place as a 'tradition', and yes they're meant to be ironic!!
Gg ...I think they make knitted jackets with scandi reindeer type Christmas designs on rather that cardigans now. But of course they are more outer wear.