Good question, but I have no answer, other than to say perhaps smoke is associated with fire and fire is nice in the winter. There might be issues related to what you say, especially humidity.
might be that ppl heating with wood are using more hardwoods that give off a sweeter aroma
outside summer fire usually are less desireable wood, dryed yard waste and the occasional old living room set.
I notice two stoke exhaust smelling much different and better in the winter. Chainsaw for example, things i run winter and summer. I notice vehicles smelling better in winter also.