I've read that cosmetic surgery and reconstructive surgery are two separate specialties. So, practicing breast augmentations isn't going to help you much when a soldier loses a breast in battle. (See Newyorker article
here ). Though, the reconstructive/cosmetic distinction may also be a load of BS. My wife worked for a plastic surgeon for awhile after college. He did both cosmetic and reconstructive surgeries.
That being said, I'm not sure that I'm against free cosmetic surgery for the military. Different jobs have different benefits. Free cosmetic surgery might be good for recruitment. (Though do you really want a soldier that joined just for the plastic surgery?)