Yes, don’t ask, don’t tell is set up to keep people in the dark, so some troops don’t freak out, or worse, discriminate or take action, against other troops.
And while the general attitudes in society may be getting more permissive towards deviant sexual activity of all types (look at the rise in teen girls giving random blow jobs to guys for the fun of it), the mentality of the “real men” who volunteer to go possibly get their brains blown out may not be the type of thinking that says “love to have a gay guy showering with me”.
They may much more likely be the kind to say “no f-ing way I’m hanging around with a f*g*t, no f-ing way I’m trusting some girlie man with my life”.
And if I was gay and in the military, I wouldn’t want to tell, because if you think the enemy is particularly cruel to women who they catch in combat, imagine what they’d do if they caught an openly homosexual soldier.
It's a volunteer army. If your battle face requires you to spout off about how heterosexual you are perhaps there's something wrong with your game plan.
How about they all take a public oath in boot camp about how much they love the opposite sex?