I've driven in the snow a lot (grew up in New England, and regularly go up there to visit relatives) and I've never had the slightest problem with snow coming off someone else's car. It either slides off in big, wet chunks that are far too heavy to fly into the car behind, or else it's just the occasional wisp of powder here and there. A moderate rain hurts visibility FAR more. So does driving within 100 feet or so of a truck on a wet road (that fine mist they kick up is annoying).

Anyway, if it really does cause a lot of accidents, then fine, maybe we need to address it. I've never seen any problems like what you're describing though. I can maybe see your point about headlights and taillights, but it's pretty difficult for those to get obstructed (as they're vertical surfaces), and they generally clear up very quickly (again, since they're vertical, and also because they get warm from the light inside).