I think it's really messed up that in the "You can be good drow, too, see?" artwork all of the good drow are pale-skinned to the point of being almost white.
Making the visual change happen right as they make it explicit that no race is wholly evil? It's very blatant "Dark = Evil, Light = Good" imagery.
As to the "Albinism makes more sense, anyhow" brigade: Drow didn't "Evolve" to be obsidian skinned. It's an ancient curse from Correllon which was laid upon Lolth and all who followed her, as well as Eilistraee.
Feel free to have albino elves in your games and settings, of course. Or Stone-Grey or anything in between. Should probably also make them Blind, honestly, if they evolved as cave-dwellers... But the default setting for 5e is FR and alllll of it's baggage! We can't ignore that when looking at new art from WoTC in a core rulebook.
Also worth noting: Even if a hundred different artists submitted work for the book, the Art Department had total editorial purview over what gets used. So this whole "Since drow can be good let's make them not black in our artwork, anymore" angle is something that hit a -lot- of desks and was approved by a whole bunch of people before release.