There's also the escalation timeline. In a hypothetical situation where nonlethal force is being used, but there's a threat that requires more than a gentle "please don't" type of heating, I don't think we'd want it to be limited. Gentle crowd suppression is great till someone pulls out a gun or knife, and though it's debatable opinion and there are a lot of factors to consider, I think a few collateral 2nd degree burns beats switching to a rifle and opening fire into the crowd.