There is no doubt that TOS didn't take on social issues on such as child abuse, drug addiction, abortion, poverty etc. GR gave it a different agenda such as war, prejudice, computers taking over the world. etc.Star Trek's fan have long given it approbation for work it never actually did, supported by Roddenberry who frequently derided the quality of TV and his need to use Trek as a Trojan Horse get little morality plays on the air. But these notions don't stand up to scrutiny when you actually see a broader swath of 60's television than what survives in syndication today. Cicely Tyson was a non-maid black female character on East Side/West Side three years before Uhura. The Defenders tackled social issues head-on in a way Trek never had the mandate/guts to do for four years before the Enterprise hit the airwaves, I Spy Had a black co-lead a year before Trek and even did an episode on heroin addiction where the addict didn't kick the habit. Etc.
Star Trek did have some progressive things to say, but it was neither unique or especially daring in that regard.
In regards to Uhura's role. Maybe she wasn't the first black woman in a non-stereotypical role, But she was one of the first taking a "man's job" that wasn't a secretary or a care giver or a nurse or an exotic spy. . On the Enterprise in TOS you had women performing all sorts of roles not just counsellors or nurses or teachers. OK most of them were secretaries but you had a navigator, scientist, ship's commander shoved in there on occasion.
I love Ellison's work and he's correct to the extent that Star Trek isn't really hard sci fi. Nether was Babylon 5. The closest things you are going to get to that (that I've watched) are Twilight Zone", maybe Night Stalker and X-Files too where they had a "monster" story and wound the regular characters around it to investigate it.
For Ellison to say it doesn't deserve its fanatical following. Who is he to say?
I don't think Kim Kardashian or her sisters deserve any sort of following but millions disagree with me.
If you like Star Trek because you think Data is funny, have a crush on 7of9 and not because of the stories or messages then are you "wrong" to like it?