My first impression is: Wow, the quality of art really fell with Tasha's. All of the pictures are comparative amateurish to the earlier ones posted, or at least of greatly diminished technical proficiency. I don't own Tasha's so I don't know if this goes beyond these pictures, though, and of course all books have included sub-par art, but it is striking how all of the pictures in the OP from Tasha's are in this vein (imo, of course, given that art is subjective, blah blah blah, but...). It makes me wonder if it was a last minute change requiring a lot of quickly commissioned art.
My second impression is: Why must all artists depict drow the same way? Isn't a major aspect of art (and D&D, for that matter) to come up with your own version of something? To make it your own, whether you're an artist or DM or player?
I'd much rather see WotC take a more varied approach, to emphasize that drow can look however you want them to look, and represent this through the art. Maybe the drow of your world have a wide range of skin colors, or maybe you like the way the obsidian ones look, or the silver-gray, or the pastel violet... it is up to you, as the creator of your own D&D world (and up to you, the artist, to depict them in a way that inspires you).
In terms of realism, it would seem the most logical approach would be to customize skin color to the climate. A general book like the PHB can and should depict a variety of skin types, but if it is a book set in, say, a desert climate, then most (not necessarily all) of the skin colors should reflect that with shades of tan, brown, copper, etc. Generally speaking, the more tropical, the darker the skin; likewise, the more polar, the lighter the skin.
In that regard, drow as dark-skinned has never made sense unless, of course, they were originally tropical, and I can't remember any lore suggesting that. And of course we used to have the very disturbing idea that they were cursed and turned dark, which is, thankfully, written out of the lore.
From a purely realistic standpoint, the new skin tone makes far more sense, drow being underworld dwelling and thus pale skinned. So it makes sense, with the caveat that I still like the idea of more of a range and variability of depiction.
D&D is fantasy, after all, so if a worldbuilder wants a dark-skinned people to live in a colder climate (or underground), why not? It wouldn't hurt the depth and verisimilitude of the world-building to include a reason for it (e.g. they left their homeland a few hundred years before), but fantasy is fantasy and creativity and fun trumps realism for most.
All that said, I would love to see WotC take an approach where there's more range within individual worlds, that while they all share the same basic lore, each world has a different take on it. To some degree they already do this, especially with worlds like Dark Sun and Eberron. But I'd like to see them take it a step further, perhaps saying in some way in an revised MM and PHB that drow (for instance) have been depicted in various ways in different D&D worlds. As with anything in D&D, it is up to you to customize as you see fit. They could then go on to offer options as they might appear in different campaign worlds: "Drow classic" for Greyhawk, Greenwood's take for the Realms, Melnibonean-esque elves, etc.