Quite honestly, the co-ed military distracts from the mission from time to time. Being in the Aviation component of the Navy, I've always had women around me. Some chased Officers, some screwed just about anybody, and some were just normal Sailors. I even had a couple of lesbians work for me in one squadron and some bi-sexual women in another squadron. I honestly didn't care about their sexual orientation, but their military orientation. They were dirt bags, to put it bluntly. I've also worked alongside closet gays. As long as folks do their job, I don't give a rat's ass.
The archaic reason (perhaps historical) is because homosexuals were usually in the closet and therefore, more subject to blackmail & violating security in order to keep their secret. All in all, they were a security risk. I don't really see that in today's military. John Walker and his ilk violated some serious security and they weren't gay. I'd like to kick John Walker in the ass because he compromised some of the gear I used to work with. His evil deeds made more work for the crypto folks and cost the military a LOT of $$$$
