It seems to me the answer to your article is where you started... how many Americans are unfit. Who would die for the system that made them unfit? That's a paradox.
The problem is not the military; it's the country that military supports. Just comparing US treatment of German prisoners of WWII to Abu Ghraib and Guantanamo... it's not the same country.
My father and grandfather were combat veterans. My father suffered from PTSD and told me if I ever got drafted he was taking me to Canada. I was Commander of my ROTC unit in high school on the fast track to an Academy. That was 1991, when Bush invaded Iraq. From then on, war was less for "our country" and more for our country's politicians. I opted out.
You're correct to mention how socially advanced the US military is in racial and gender equality, health care, education, and even the bleeding edge of technology and environmental sustainability. Most generals even argue against war.
If society were anything like the military, taking care of my health, valuing my education, progressing science, building my character, arguing against war, sign me up. Until then, I'm sticking to my first choice - I left America altogether.