Kids do get hurt and that's fine but as a parent I wouldn't be happy if my kid got hurt because of a game he wasn't even part of. Not all schools have large playing areas and a ball game can take up most of that playing area. When my my oldest went to school in New England they had a very small playground and the grass was out of bounds in the winter/ fall because of the mud which meant they were restricted to the playground and the tarmacked area. If they were to play football (soccer), baseball, dodgeball etc it would of taken up a lot of space forcing the kids who didn't want to play or were afraid of being hit by the ball out of this area. So the school restricted ball games in the winter and the kids found other things to amuse themselves with. After school my son played football with his friends, played on a team at the weekend and the world didn't end.