There is a lot of racism shown from the sides of Klingons, Ferangi and other species, but I have always felt Star Trek has done a good job of painting racism as a negative thing, and shown the Federation to meet all alien races with open arms. Perhaps I am wrong on this. Mind citing a few examples of aliens needing to act more human in order to become better?
In a broad manner Trek does (the white/black vs. black/white aliens) but when you really look at HOW these races/cultures are written I think you see a lot of racist ideas. Notably, how species and culture are the same thing, unless your human. Only humans can have variety.
I think Spock's long term arc of being more human and embracing his friends is portrayed as a positive (this is strongest in the movies). Spock's influence never influences a human to become more logical and less friendly.
The Ferengi teenage on DS9 had to learn to be more human (less greedy, brave). Cisco's kid was never shown to learn to be more like a Ferengi (and if he had, it would have been seen as a bad thing).
Worf needed to learn to be more human to deal with his spinal injury on TNG. A Klingon would have just killed himself. And Picard TOOK WORF'S SIDE, insisting that no Klingon could adapt to what he'd expect a human to adapt to, even a Klingon raised and living among humans.
Im not sure, but I think the half-Klingon on Voyagers second line ever was "I'm sorry, but my Klingon half is forever warring with me!"
Given that we have had zero known contact with extra terrestrial lifeforms, I just don't think the science is there to prove this. Yes, it is true with earth species, a dog can't mate with a cat. But I am more than willing to suspend disbelief and go along with the idea that various alien species in the galaxy have evolved so closely along the same lines that they are able to produce viable offspring with one another. Ultimately, it is pretty ridiculous that all these different aliens look so much alike. At the end of the day, you could peg the "bad science!" label on every single sci-fi and fantasy story ever told.
I'm not attacking that they all look human. That's a reality of TV/Film production. But if Vulcans and Romulans have a common ancestor and can breed, they are the same species. That's what 'species' means.
Really, I've always hated the 'Star Trek has real science' argument. Of 'Star Trek is for grown ups.'
Star Trek wraps itself in nonsense technobabble, but has NO more science in it that Star Wars. Star Trek even spends half their time dealing with various 'omnipotent aliens' who for all intents and purposes are evil gods. And just because the chick in the leotard on the Enterprise says she's an alien telepath, as far as I'm concerned she's a Force User, with as much science as that contains. The Genesis Device has no more merit than the Death Star.
And if every sentient species in the galaxy can mate, that's just magic.