Lambert ... wokey?

It needs to be justified because it's part of a story he's telling. Dallas has a beard because it contributes to how viewers perceive the character. Ridley Scott needed a confident, powerful leadership figure for the captain, both to quickly show viewers this guy's status on the boat, and later (SPOILERS - in case anybody needs that warning for Alien...) to give us a jarring shock when the "stern, confident hero-type person" gets snuffed out by the monster. We feel adrift without the captain, and the fact that a movie shows us this strong-jawed, beard-having hero and then just kills him - that's useful for storytelling. "Brett wears that shirt," because the crew of the Nostromo are blue-collar workers. Scott wants us to see "space truckers," so he's got a ballcap on and a Hawaiian shirt shows us the kind of sardonic, Budweiser-drinkin' Joe who thinks it's fun to wear Hawaiian shirts. I actually get a lot of information out of costumes that characters are put in, and that's why movies have costumers.

Decisions made on sets aren't random. Any information is worldbuilding. It's possible wanted to alter Lambert's sex because he was making a feminist statement. Lambert was (my opinion) the most fragile of the crew members, and maybe Cameron wanted to create a world in Aliens where females were tougher so he could make the final confrontation between Ripley and the Alien Queen one of female dominance. Mothers and their ferocity come up as a theme in Aliens, so maybe that's what Cameron was doing. It could be that he was showcasing tech (my theory). I don't know. Those are just guesses.

James Cameron is particularly known for being ultra-focused, extremely hardworking, and detail-oriented. This guy didn't just randomly ask to make a major change to Lambert out of nowhere. Unless the change didn't come from Cameron. The only other explanation is either Dan O'Bannon put that detail into his script (unlikely, since I understand that the characters weren't pre-conceived as sexed until casting), or it was put into the novelization or something like that.

At the end of the day, when a detail-oriented perfectionist makes a major alteration to a character created by somebody else, it should be significant. Any story details are important, especially when altering somebody else's work.

Finally: to state that altering a character's sex is insignificant is to state that sex has no bearing on characters at all, which isn't the case. If it were, you could ask, "Why is it important that the Alien Queen be a mother, not a father?" It's because you lose thematic material on motherhood. "Why couldn't they make Mean Girls about men?" They could, but it would be almost unrecognizably different because the female high school experience is a very different thing.

I don't like being given propaganda when I was told I was getting entertainment. I know that it can be a fine line sometimes, but when I get the sense that I'm watching a commercial, I start rolling my eyes. If the whole movie feels like a PSA, then I don't like it.

But none of that impedes my ability to enjoy material with progressive ideas in it. I have enjoyed both Arcane and Blue Eyed Samurai, for instance. I don't know if you've seen those shows, but they're both really great (I would recommend them) and both are filled with the kinds of things that get accusations of "woke" leveled at them. However, neither of them - my opinion - feel like they are preaching at me, so I like the shows.

It's the difference between Martin Scorcese's film Silence and the Pureflix film God's Not Dead. Both are films about Christianity, but one is a breathtaking exploration of faith and doubt and the other is a condescending lecture without nuance or subtlety. You can love or hate Christianity and still recognise that one is a great movie and one is horrible.

In summary: there is a difference between progressive ideas and "Woke" - for me, anyway - and part of that in film is about how nuanced the film is.

You're talking to our resident woke troll who has countless of socks.