Another reason for the fly is it sheds snow easier. My first wall tent was a brand Cabelas no longer carries and it was a budget model nightmare. The fly didn't fit the canvas (stove pipe hole was in wrong place), the frame didn't fit right, and it was too cheap. It collapsed under snow load when I had to leave the site for an extended period with no heat.
My second and current wall tent from Panther Primitives was bought for using at reenactment events, but became an extra outpost for family deer hunts out of my father's motorhome. Having more room and a place to dry wet clothes was quite an improvement! With no fly, it has withstood a 2'+ blizzard and subsequent thaw without any dripping inside, but the walls were damp inside if you were to touch them. Keeping the stove going makes a big difference, of course.
If you're not camping next to the vehicle or have pack animals, you're not going to get very far in, comfortably anyways. We once used a deer cart to set up about 1/2 mile from the vehicle on a log road in the snow, and that was some kind of work. Even harder bringing out wet canvas to be dried out again at home. Lots to consider, but defineitely lots of enjoyment!