I think this is the most troubling aspect of racial essentialism in many RPGs: all races, besides humans, are conflated one-to-one with a single culture, and many races are conflated with some notion of absolute evil. This is troubling to my mind, in that it suggests that, despite having the capacity for free and rational thought, a whole 'people', 'race', 'species', or whatever you want to call it, can nonetheless be evil by design/nature. It suggests that individuals of that type, despite having a more-or-less equal conciousness to that of humans, are unable to reason their way to a sound moral position, and are therefore (in the case of many 'monstrous' races) deserving of extermination wherever they take up residence./snip
Of course, there is still the in game realism to take into account. Orcs are evil because they are made that way. In a sense, when you have provable Creators, then racial essentialism becomes truth. X is that way because it was MADE that way. The Gawds put a lump of putty in their hairy armpit and out squished the races.
Scarred Lands, for example (one of my favorite settings) posited that most beings are created by these massive elemental beings known as titans. There are a few created by gods, but, they're almost always servitor races with little or no free will.
But, it does make sense, at least from a setting standpoint that you would have races with pre-determined behavior, simply because they didn't evolve, but were made that way.
That's because they are aliens.
They also would appear to be "hypothetical groups of sentient beings with more or less the same thinking/feeling capacity as humans".
I have a problem with this. Other than the Queens, there is no evidence in the movies that the Aliens are anything more than particularly smart animals. Even the Queens are not portrayed as particularly intelligent. They use no tools, they don't appear to communicate in any way other than basic concepts common to most animals. They travel through space on a hijacked ship they didn't build.
They aren't really moral beings at all, any more than a shark is a moral being. At least, IMO.
That's an entirely valid idea, but it seems to assume that the races in question must have "grown up" (or evolved, if you will) in very close quarters and leaned heavily on each other.
Most fantasy settings with multiple races I'm familiar with assume that the races started in separate areas, or are otherwise not coming in contact with each other every day. You'll get "melting pot" cities where a lot of races come together, but each race still keeps its own unique cultural identifiers.
/snip
I'm not really sure how realistic that is honestly. Given the technological levels of fantasy settings, you're probably looking at thousands of years of coexistence and migration of populations. More than enough for populations to mix. Sure, there would be isolated populations, that's a given, but, most races are not that remote - certainly not the base PHB races anyway.
Dwarves maybe because they live in the mountains. But Halflings or elves? They're cheek to jowl with humans.
But, even that's not really my issue. It's that every race other than humans has only one culture. If you reduce humans to mono-culture, that would be one solution, although perhaps not a very satsifying one. I would just like to see a setting where you have a number of different, and significantly different, cultures for each race.
To use a 4e thing, look at the Eladrin/Elf split. Eladrin and Elves are the same race, but have significantly different cultures due to their baseline assumptions. Fantastic. Now, I want the same sort of splitting for halflings, tieflings, dragonborn, and dwarves. The Eladrin/Elf split is not enough IMO, but its a good step in the right direction.