There's enough really cold days where I live to justify owning 2 insulated (1 down, 1 synthetic) jackets. Pit zips and hood give them about a 25-30 degree comfort range from around +30F to -10F, and I'll still layer underneath at -10F, but don't usually need more than a fleece and a base layer.
There's also enough warmer days that I can absolutely justify owning a shell too, mostly for temps above 20F, but can go colder with more layers, or warmer by shedding layers, or using pit zips.
Serious question: Do any of you actually try to get through an entire season, or multiple seasons with just one jacket?
Another serious question: Do you own jackets that you only use for skiing?
I'm an admitted gear-whore, so of course I've got multiple jackets. Shells, insulated coats, both down, and synthetic, insulated micro-puff, fleece (duh), and even a dri-clime wind-shirt that doubles as a mid or outer layer. I don't use my shells for much besides skiing (BC & IB) or maybe hiking, but really like the down for any situation where it's even moderately cold, and I don't expect to be moving around much (Christmas Tree lighting, dog walks in town).
I've bought pretty much all my stuff on closeout, and never paid over $200 for a jacket, so don't feel like I have to limit myself to a single jacket, or layering option. Of course I forfeit the ability to criticize others for not doing it my way, since I do it multiple ways, but hey, that never stopped me before.
What do I want in a ski jacket? Simple, two jackets or more. The rest of you are doing it wrong.