Why is it that a lot of winter boots aren't waterproof?

You go to a shoe store and they sell these "fashion winter boots" that aren't waterproof. They always tell you to spray them but the sprays won't help especially when the leather gets destroyed by road salt. Popular boots like the ever hideous Ugg are impractical for winter because they get salt stained so quickly and they aren't waterproof. The waterproof boots they do carry are generally dowdy and old-ladyish. They can't they make stylish durable winter boots which are stylish and have soles and heels that aren't worn down by road salt? Or waterproof boots that are warm? Rubber boots don't keep you warm when it's -30C outside.