The problem with Kent State was that instead of firing at the leaders of the trouble-making rioters, the national guard fired over their heads striking bystanders in the background. Rioters are generally like packs of wild dogs - take out the leaders and the rest will flee.
You are exactly right. The Ohio Guardsmen were Guilty of horrible aim (I.e. They missed all the rioting Hippy freaks and hit innocent bystanders walking to class.)