This whole shower thing is simply rediculous. SOme barracks have stalls, some barracks have open bays, I haven't seen barracks that have both. That being said, there are no barracks that have males and females sharing showers, regardless of the configuration; hence, gays and straights can't be forced to share billets; per the commandant of the Marine Corps.
Yes the whole shower thing is ridiculous. How often do soldiers actually have to shower together in open bay showers, outside of training environments and punishments quarters? Possibly in the field, although, from what I have seen and heard about those, they are still separated stalls. Even on ships, we have separate shower stalls. My husband was in the barracks at K-Bay, he shared his bathroom with one roommate. I'm pretty certain they didn't have to shower together. Now I do know that there are barracks where you have to share a complete bathroom with the adjoining room, but, to the best of my knowledge, these have locks inside and out, like the one I stayed in with my husband when I visited him during his training at Lachland.
All this said, as was mentioned before, college students have some of these same situations in their dorms. There are also similar shower situations in gyms and in some other professions as well, including policemen, firemen, and some doctors. Amazingly, only the military seems to have such an issue with having openly gay personnel showering with straight and closeted gay personnel. In fact, if a gay guy/gal were determined to constantly get peeks at their fellow showerers, they would most likely stay closeted, and the military would have to go through the effort of proving they are gay to get them put into the gay berthing/shower area. Doesn't make a whole lot of sense to me.
Furthermore, how do you prove someone is gay if they do stay closeted about it? Removing restrictions on gay personnel serving will not make it mandatory that everyone declare their sexuality prior to entry. In fact, this would be quite useless, since there are many people who might not know what their sexuality is even upon joining. Some may be in denial due to personal issues with homosexuality. Heck, there may even be some people who say they are gay just to be in a smaller berthing/shower area.
The sharing of berthings and showers is a weak argument because gays and straights are sharing showers now, men and women aren't.