" Lastly, U.S.M.C. which does a lot of the fighting and dying ..." is very misleading when it comes to the dying part. In the last 3 decades of war by USA against majority Muslim countries, USMC war deaths might well exceed 1000, but likely far fewer than 10K. Deaths of people in the target countries caused by these wars are in the several millions. (Most of the deaths were not directly caused by bombs and bullets, but they are war deaths, just like leaving a baby in a car in the sun for a day in hot weather is a homicide, although in the latter case the homicide is not intentional but careless.)
It is fair and accurate to claim one of the reasons USMC casualties are so much fewer is that there are nowhere near as many Marines as people in target countries, and one should look at death rates. I do not have a good estimate of death rates of USMC infantry, but I recall one news article that gives some indication. It stated a certain Pendlelton based battalion had about 60 war dead in a period of about 5 years or so. I do not recall the battalion size, but 500 is near the middle of the current range. This yields a death rate of 12%. When it comes to war caused death rates of pre-school aged children in Iraq during significant portions of the last 30 years, 12% is near the middle of the range of the best estimates. (In 1996, US Ambassador to the UN Madeleine Albright accepted the medical study that produced that rate estimate, with a total around half a million young child deaths, and commented "we think the price is worth it".) (As I recall, that battalion was described as one that had one of the highest death rates, not average, but I may recall incorrectly.)
When one drafts people who think like law abiding civilians, whether male or female, that group is likely to have many who question the wars and note who is really dying. These people may "infect" their units with the idea that what they are trained to do, and likely to do, is kill civilians including babies, in huge numbers for reasons and results that are counter-productive to the cause of national defense.