Well it's true that unless gay characters are all ding-a-ling-a-liiing~ :heart: then they tend not to be detectable at all, but that isn't really something inevitable. I'm not aware of any game that pulls off a non-player "straight gay" (i.e. a gay character who doesn't really act in a stereotypical gay fashion). It's possible there's something out there I just haven't played, but you never really have a normal party member who just happens to be fighting to save his boyfriend or anything like that. You could say "Well why bother if it's barely going to be touched on?" but I would say "Would it really be so bad if it's like that?" Of course, I imagine the business standpoint is probably "Conservative America dislikes gays, so there's no reason to risk losing money when we're not making a statement".
I don't really give a whole lot of credit to player characters who have the option to be gay, since that's more about player choice than open-mindedness.