I respect your opinion, but I don't see things quite that narrowly. "Thank you for your service" means exactly that: Thank you for serving your country. It's especially apt for those unfortunates you mentioned, but my understanding is that it applies to all those who gave up years of their lives in military service. I'm sure that's what most people mean when they acknowledge a veteran. When we were inducted we all ran the risk of "coming home disfigured, wheelchair bound, missing limbs, etc." Veterans (and I am one) are being thanked for protecting others. George Orwell perhaps said it best;
"People sleep peaceably in their beds at night because rough men [and now women] stand ready to do violence on their behalf."