AfterElton has an interview up with a Star Trek writer/producer, Brannon Braga, on why the franchise never included an out gay character. He doesn't really answer, implies that the problem was unnamed people who worked on the show twenty years ago....
I recently rewatched all the Star Trek movies and was surprised not just by how progressive the franchise was - the future has all races working together, women in positions of power, and problems usually solved by learning to interact with a new species - but about the specific brand of hippie-ness in the older movies. There's a scene in Undiscovered Country where a Klingon accuses Uhura of racism for talking about "human rights"; Kirk's son in The Wrath of Khan goes on an anti-military rant; and the entire message of The Voyage Home was that our survival depends on biodiversity (that and "Whales are sentient"). Oh, and money doesn't exist in the future and everyone's taken care of.
So you'd think introducing a queer character wouldn't be too hard in that context. But apparently it was:
AE: I'm very much a fan of Star Trek but unfortunately none of the series ever included a gay character. You were involved with writing two of the movies and produced or executive produced for The Next Generation, Voyager and Enterprise. Can you speak to why that never happened?
BB: It was a shame for a lot of us that ... I'm talking about the Next Generation, Deep Space Nine and there was a constant back and forth about well how do we portray the spectrum of sexuality. There were people who felt very strongly that we should be showing casually, you know, just two guys together in the background in Ten Forward. At the time the decision was made not to do that and I think those same people would make a different decision now because I think, you know, that was 1989, well yeah about 89, 90, 91. I have no doubt that those same creative players wouldn't feel so hesitant to have, you know, have been squeamish about a decision like that.
This from a show that gave us Uhura. Here's Nichelle Nichols, who played Uhura in the original series:
One of the organizers came up to me and said that there was someone who wants to meet you; and he says that he's you're best, biggest fan and I'm thinking it's a Trekkie! [laughs] and so I said certainly and I got up and turned around and maybe 10 or 15 feet coming towards me I see Dr. Martin Luther King and I remember thinking whoever that little fan is, he's going to have to wait, because here's Dr. King, who walks straight up to me with this big, magnificent smile on his face and says, "I'm the fan!" because I'm sort of looking around for someone else, and he says, "I am your best fan, I am your biggest fan!" and I... I was at a loss for words, and if you know me, I am never at a loss for words.
I just couldn't say a thing and he began to tell me how important my role was, what an inspiration it was. And you have to understand we were in the middle of the Civil Rights Movement, people were regularly being attacked by dogs, and marchers were being hosed on the television every night, real life things, and here I am in this futuristic thing on TV and he was so complimentary, he told me "I was so important and the way you have created this role," and I am just looking at him and looking at him and I remember I just kept hoping he'd never stop talking. Because his voice is just... you know the voice. And I finally just start saying, thank you so much Dr. King and I am shaking his hand and still shaking from nervousness and I said thank you so much and I am really going to miss my co-stars.
And at this his face totally changed, and he said "What are you talking about?!" and so I told him I would be leaving the show, because; and that was as far as he let me go, and he said, "STOP! You cannot! You cannot leave this show! Do you not understand what you are doing?! You are the first non-stereotypical role in television! Of intelligence, and of a woman and a woman of color?! That you are playing a role that is not about your color! That this role could be played by anyone? This is not a black role. This is not a female role! A blue eyed blond or a pointed ear green person could take this role!" And I am looking at him and looking at him and buzzing, and he said, "Nichelle, for the first time, not only our little children and people can look on and see themselves, but people who don't look like us, people who don't look like us, from all over the world, for the first time, the first time on television, they can see us, as we should be!
This is a show that didn't mind, at one point in history, being ahead of the curve.
Now if they launch another series or produce another movie (one's in the works), they're not going to be ahead of the curve or the first show to have an openly gay, bi, or trans character who's accepted as a peer - there already are plenty of other shows with that.
Still, one hopes that they would eventually get around to that. When I imagine a utopic future, people aren't all straight and avoid talking about same-sex love.