I don't know how many people are actually surprised that there's a culture of brutality in the Marines, but this article gets it mostly right. How prevalent is that culture of brutality? It was hilariously pointed out to me this week that if you pull up MCRD San Diego on Google Earth and zoom in close enough you can find a lone recruit with his face in the dirt getting smoked by a Drill Instructor. But this brutality serves many purposes.
It elevates the natural human threshold for pain. It hones focus. It conditions Marines to do violence on behalf of those who cannot (or will not). It's a tragedy whenever someone dies during this training (especially under the circumstances of this particular case), but you have to think about the product that the Marines are manufacturing. If you really want a fighting force who will run toward the gunfire, then the steel of that reserve must be tempered somewhere.