Savage Wombat
Hero
Pen, I think you hot on what bugs me. The older dnd monsters had lots of demographically important bits but rarely tried to fit things into a larger story, epic or not.
The 2e Monstrous Manual entry on kobolds has tons of "biological" information about kobolds but nothing about history.
Honestly, that's what I want.
But when the MM tries to fit demons and devils into a larger mythical history you don't want that.
I don't want my PH to tell me that dwarves are a former slave race to giants - that sounds like the kind of racial baggage that would go against the world building I do. Saying "they live in mountains and hate orcs and goblins" lets me decide why for myself.
I think these discussions keep boiling down to "I prefer the story I liked" and that these "explanations" are merely rationalizations.
Some people liked the World Axis, and some people didn't. There's no "better".