I have no objection to any of the above comments. The choice is for everyone to make based on their desires and experiences.
I have owned and lived on my ranches in Colorado Since 1961 and 1987, both ranches in the Mountains. Over the years I, and my employees, and family, have owned both 4X4 and 2X4 trucks. I still own both types.
I have two Dodge D-3500 2X4 trucks that are the only ones that I use when pulling, not only our 5th Wheel RV, but also our horse, Stock and Flatbed trailers when on our Colorado roads, driving for any distance. I have not pulled any of our 5 RVs anywhere for over 50 years with a 4X4 truck. We use our 4X4 trucks on the ranch when driving off road and in normal day to day ranching work activities such as fencing, servicing machinery in fields that are rough, ditched, often wet, etc.
It is true that Colorado Mountain roads tend to be icy many times in winter months. Mountain highways are solid pavement and many county roads are hard surface gravel surface. I can't remember ever having problems with mud, soft roads, etc., in Colorado when on the road. It is only off road where those conditions are common.
Since studded tires were invented in the late 1960's by Coors Porcelain Company, I and most of my employees have seasonally changed to studded winter tires on our light trucks, both duallys and SWD, and autos. Every Fall, about October, I put studded tires on the trucks and cars. Usually in May I have the summer tires put back on. Our experience is that studded tires all around are at least equal, and I believe better than non studded tires on 4X4's tires on ice and hard packed snow on roads. I know for sure that studded tires, all around, on 2X4 trucks are much safer when going down hill, both in lower gear and braking, on slick roads, especially when towing a trailer, than a 4X4 with non-studded tires. It is the down hill performance on slick roads, not uphill on a icy road where accidents are most likely to happen in the mountains.