OK, so, throwing snowballs can be fun, with a bunch of mates, if you're dressed for it (even I was young once)
BUT
collecting a load of snow, packing it down into a lump of ice, and hurling it into the face and/or windscreen of random passers-by is unpleasant and potentially dangerous. It could get into their eye, probably will get down their neck and in the case of vehicles, could cause an accident. If you were to throw anything other than snow into someone's face or at someone's car you'd be in big trouble, right? So why does the fact that it's cold and made of water let you off being able to attack strangers with hand-made missiles?
There should be a law against it. I suggest a suitable punishment would be being placed in the stocks and pelted with, guess what - snowballs. I may or may not feel humane enough to allow the prisoners to wear goggles to prevent eye damage, when I've cooled down a bit.