A lot of ultralighters are suffering from the backpacker's equivelent of anorexia. They aren't in the right mindset. These are the guys you are talking about, and sane, safe ultralighters would mock them.

There IS ultralight winter gear. It's expensive, and I personally don't think it is up to severe cold, it isn't horrible. My only grumble is that a lot of ultralight gear doesn't strike me as being as physically robust, but that is becuase it is designed for the trail, not for true cross country. I generally assume that I'm going to have hump my BOB through two miles of brambles and young brush becuase it saves four miles of road hiking, and/or I'll be tossing it and the back of me from the back of a pickup at some point.

That being said, I wish more people used 500D Cordura- 90% the strength and 60% the weight of 100D. And that is just one example. Aluminum and titanium rather than steel. Plastic, rather than glass. Carry one lexan spoon and one lexan fork. Lithium rather than alkaline batteries. There are always things to learn from ultralighters.