I never follow people too closely in this weather so I never have paid much attention to snow falling off their vehicle.
These are the same drivers who think that because their car isn't moving or isn't moving fast enough that they must give it more gas. I can't count the number of times I've seen that this week. The only time I got out of hand was due to the packed ice, sent the back of the car out left about three feet or so at 15 - 20. I think the guy coming toward me was a little worried I just thought weeeee.I've been driving in this crap all week and the VAST majority of the cars guilty of the OP's observations have no luggage racks, those vehicles I understand. They are cars and other small vehicles where the driver was too lazy to take a few minutes to clean off their car. In fact, many of them just clean a very small peep hole in the windshield and that is it. I don't hate them, I just shake my head. I shake my head at sooooooooo many drivers this week. Drivers that feel that to prevent getting stuck on a slick bridge, one must spin the FWD tires so fast as to create a white cloud obscuring said bridge from view. Drivers that see my flashing red/blue lights as I shut a bridge down and figure it means all they have to do is go around me. Or the driver of a 4x4 yelling at me for shutting down the bridge saying that since he has a 4x4 he should be allowed to pass. Or the driver of the car traveling in front of me as we both go 25mph in a straight line and for some unknown reason starts spinning out of control. How the hell does that happen? I have seen cars off the road at angles and positions that leave you scratching your head. I don't HATE anyone but this week was awful and my view of drivers has dimmed.
The roof or trunk is one thing. Those who don't clear their window to see are just plane idiots. Why would you not want a clear view of everything around you as you would on a sunny day? I prefer to see what's going on around me, particularly when every other moron is a potential out of control heavy metal missile.