Okay, we need to be talking about the same thing here. Which is otherwise straight female characters leaning towards women. Not any kind of sexual attractiveness from any female character ever.
My initial reply was in both to male gaze related things and also the general atmosphere writing to that view can often lead to; which is that it uses womens sexuality to sensationalize and tantalize for a male audience. Jack and Miranda are gonna kiss? Who is that comment for exactly? Jack would sleep with fan favorite straight romance Tali if she was drunker...who is that for exactly? Asari at ...every night club. I think Ashley explained that pretty sucinctly when she first steps foot in Cora's Den.
I love the Mass Effect series to death, and this is certainly not a Bioware specific problem, its a media one, but these things are all done for the straight male gaze/straight male audience. Furthermore, teasing straight women characters making out with another isn't representation or LGB content. Its simply a perpetuation of the same problem that diminishes and disreguards real women with real same sex attraction. So yes, I notice this stuff when I play the games.
I'm thinking female homosexuality being more acceptable, in any case, is still a product of the patriarchy.
Someone said this one thing that has always resonated with me: Straight men are afraid of gay men because they think they'll treat them the way that men treat women. So I think you were on the money in one of your other posts where you said something along the lines of female homosexuality being less threatening.
Male gaze... patriarchy... same same. 
Anyway I would be over the moon if we could see wholesome, sweet gay romances in future games, like some of you guys are suggesting. And hetero romances that women can enjoy without getting their ears talked off about the guy's ex.
I wouldn't say female homosexuality is more acceptable...so much as its...disreguarded to an extent? Like you said, it doesn't threaten men, so why would they be so concerned about it?
If a 12 year old boy kissed another boy, no one is really going to argue that he was confused or they're just friends because why on earth would a guy risk their image of masculinity by being gay? Vs. a girl in the same situation, she'll grow out of it, it's a phase, oh how hot can I watch you two? Even female homosexuality which should by its very nature have nothing to do with men, gets turned into something FOR men.