I don’t think you fully understand the America of the 60’s nor understand Star Trek if you are calling it “vaguely progressive “.
America and American TV was predominately centered on being white and male.
Then here’s Star Trek. The command crew has a black woman officer (Uhura), former enemy of the US (Sulu - Japanese), and current enemy (Checkov - Russian) all working together.
That was extremely progressive for the time. The circumstances around Uhura’s and Kirk’s kiss in Plato Children was basically to get around studio interference. (This kind of interference was still going on into the 00’s with resistance to allowing Willow and Tara to kiss romantically on Buffy)
I’ll also add this story Nichelle Nichols (Uhura) told about what Martin Luther King said to her about the show to reiterate how progressive it actually was. (Actually heard this story from her when I met her in person)
Ms. NICHOLS: I went in to tell Gene Roddenberry that I was leaving after the first season, and he was very upset about it. And he said, take the weekend and think about what I am trying to achieve here in this show. You're an integral part and very important to it. And so I said, yes, I would. And that - on Saturday night, I went to an NAACP fundraiser, I believe it was, in Beverly Hills. And one of the promoters came over to me and said, Ms. Nichols, there's someone who would like to meet you. He says he is your greatest fan.
And I'm thinking a Trekker, you know. And I turn, and before I could get up, I looked across the way and there was the face of Dr. Martin Luther King smiling at me and walking toward me. And he started laughing. By the time he reached me, he said, yes, Ms. Nichols, I am your greatest fan. I am that Trekkie.
(Soundbite of laughter)
Ms. NICHOLS: And I was speechless. He complimented me on the manner in which I'd created the character. I thanked him, and I think I said something like, Dr. King, I wish I could be out there marching with you. He said, no, no, no. No, you don't understand. We don't need you on the - to march. You are marching. You are reflecting what we are fighting for. So, I said to him, thank you so much. And I'm going to miss my co-stars.
And his face got very, very serious. And he said, what are you talking about? And I said, well, I told Gene just yesterday that I'm going to leave the show after the first year because I've been offered - and he stopped me and said: You cannot do that. And I was stunned. He said, don't you understand what this man has achieved? For the first time, we are being seen the world over as we should be seen. He says, do you understand that this is the only show that my wife Coretta and I will allow our little children to stay up and watch. I was speechless.”
Each of the next several series continued to be progressive.