Aside from the whole cold thing, the biggest reason why I don't ride in the winter is this:
Road salt is something with which those from states where it rarely snows are not familiar. It gets everywhere. Bikes are full of nooks and crannies where it can find a place to accumulate, and bikes are a giant PITA to clean. Maybe impossible if it's cold enough for salt to be used in the first place, which means leaving it until spring.
I've long been in the habit of parking the bike before November brings gray, miserable weather and the distraction of holidays, and pull it out in the spring after the road salt and sand have washed off the roads.
As a result, my street bike (5 years old with 14k miles on it) is in near-new condition.