Thing to remember about realms lore is that the lore itself generally represents either factual historical details, or general principles of the present day and state of things. The latter isn't an absolute to-be-abided-by thing, and in fact most stories within the realms are about strange or unusual occurrences, where the norms are altered in some way; as long as it's made clear that the unusual situation is unusual, that's just dandy.
I perfectly agree that Larian might take liberties and create their own settings. They just shouldn't be too confusing and immersion breaking.
In the present realms date, there are more drow interacting with the surface world than ever before, and more surface-dwelling drow than ever. However, drow that still serve their great houses are still generally only above ground to raid, or on very specific missions. This doesn't mean that a surface drow who broke away from their society can't just as easily opt to pursue a life of crime or villainy; their motives can be as varied as the motives of any other sentient being. The zhentarim in particular employ a lot of surface drow who have fled their underground caste and society, but still have the skill set suitable for the black network.
I liked my drow being evil and arrogant, having them as common criminals is a bit boring. I guess that this is a 5e change to allow Drow player characters?
Tieflings are not enigmatic and special, particularly. [...] In the game right NOW though, we have an active divergence from that norm, because of recent events in the realms lore - the descent into Avernus of Elturel, a city on the coast, has resulted in a greatly inflated number of tieflings being present - some who were transformed as a result of the descent [...]
If Tieflings are nothing enigmatic and special, then that's a bit of a letdown. If they are just humans with horns, what do we need them for?
It clashes with them not just having some unusual features, a little horn or something off; you see people with infernal eyes and tail, looking literally like devils - and then telling you they are afraid of Goblins. It simply comes across as unhinged and funny.
Not in the realms. Gith are far, far more alien and unusual than tieflings, by a long, long shot. People know what tieflings are, and recognise them. They may have prejudices or biases, but they also know that tieflings are a thing, and that they live lives and run businesses and work jobs. Most common folks, on the other hand (including tieflings, just as any other race is included here), aren't likely to know what a Gith is, or recognise them at all. They might think a gith a fiend of some sort, at a glance.
Just from looking at them, Tieflings look much more sinister and alien - and the Gith girl does, in fact, look comparatively "normal"
The players are humans, they don't know that Tieflings are supposed to be "normal" - they'll judge by their appearance. And they also don't know that Gith are supposed to be "alien" - they will compare them to the Tieflings and think Lae'zel is more of a girl next door.
Call this one a limitation of the current game; they shouldn't. The Cambions fiendish features should be visibly more pronounced.... but it does sound from your comments that you're not familiar with tieflings in general. They aren't new to the game lore; they've been in the game since 3rd edition, as a playable race (maybe earlier? I'm not certain).
Yes, depicting them as "only" having a horn, unusual eyes or a tail would maybe be less "cool" than have someone with red skin, flaming eyes, horns and tail. Which is probably why Larian made these features more prominent.
I know them as NPCs in 3.5 etc. Not as player characters. Including them as player characters is fine, if you can come up with a good backstory and write different reactions (Which is a lot of work).
