Sci-fi pet peeve #1: Treating different species of alien like they’re just a different race of human,.
It’s a common criticism of sci-fi; the lack of any real alien aliens. Just humans with make-up and and a vagina stuck on their head or something like that. But their culture and behavior all essentially human. Or ‘variations on a human theme’ as Carl Sagan put it.
I think a lot of the reason for it has to do with television; obviously when they made the old serials and TV shows there wasn’t the time or technology to create really convincing aliens, so they just stuck a pair of ears on someone and told them to go out there and act alien.
There’s also the problem, I suppose, that humans feel more empathy for something the more closely it resembles themselves, hence why we like ‘cute’ animals like cats and dogs, but not worms and insects. Because of that, I guess making alien characters an audience likes is difficult unless you give it a face and more human-like emotions.