Levistus's_Leviathan
5e Freelancer
Absolutely depends on setting. Dark Elves are described culturally in an Exandria/Wildemount book, and are described differently in a Forgotten Realms book, in my recommendation.So each lore book would have the races and their attribute/skills/innate abilities or a few of those things. Is that where the information would be? So the dark elves of one place may have different stat/skills/innate abilities from the dark elves of another place. I don't mind it. Sounds good. Would caste/wealth be in those descriptions as well?
I doubt I have time to write a PHB, but if I get time, I could try doing the race section, which is practically the only thing I would change in the PHB besides some mechanics.I do think if they made the PHB like this, it overlooks the exact nature of D&D (one could say one of it's core elements): pre-existing lore that has not been changed (example: the gods are around); a base of knowledge inside the PHB that has always been there (darkvision); and the fact that D&D really is, despite all its fantastical elements, a very specific setting. Not sure that would sell well. Why don't you try writing it up. I'll read it. Who knows, you may be on to something.