I agree. That's why it irks me when someone proclaims it sexist when looking at it through the lens of 2021. And it's not just Star Trek. This sort of thing is going on with many old TV shows. I was just watching a youtube video about all the things "wrong with" The Flintstones. Of course, that judgment or wrongness was made by someone making the video in today's social climate. I'm not suggesting that just because something was considered acceptable in the past and isn't now, we should ignore it. I just despise judging things based on 50+ years hindsight instead of within the time it was made. No doubt some of the currently held ideas that are considered to be enlightened and an improvement over the cultural mores of past decades will look similarly archaic 50 years from now.
I don't think past works should be thrown out because of their deficiencies, but it is absolutely worthwhile to acknowledge their deficiencies and the ways their portrayals or attitudes may be hurtful to segments of the audience. Nobody deserves to have that forced on them, so giving people information about the contents of a work, including its potential offensive elements, is the responsible thing to do. It's not about "cancelling" things, or it shouldn't be. It should be about informing people of every aspect of a work, the positives and negatives alike, so they can make well-informed choices.
After all, there's no requirement for everyone to like the same things. Letting people know that a given thing may be hurtful to them doesn't mean that other people can't go on enjoying it. It's like allergy information on food products. If I see "This product contains peanuts" on a food package, I don't take that as a criticism of my enjoyment of peanuts. It's not directed at me at all. It's for the benefit of other people who would be harmed by peanuts. The people who don't want it can avoid it, and the people who do want it can still have it. It doesn't have to be any more complicated than that.