Hussar said:We can't have a core setting with a different cosmology, without first paying lip service to Planescape.
I mean, everyone got up in arms about adding dragonborn and tieflings to Forgotten Realms. Yet, for some reason, we're supposed to just accept that every single D&D setting MUST be in line with Planescape lore.
It was AD&D lore before it was Planescape lore (see the PHB and Manual of the Planes). It was already part of every AD&D setting before Planescape came out (except Dark Sun, which isn't reachable in Planescape). Planescape just added more detail to the AD&D cosmology that already existed. As far as I know, the only things that are actually "from Planescape" are Sigil and the factions (and a few creatures).I mean, everyone got up in arms about adding dragonborn and tieflings to Forgotten Realms. Yet, for some reason, we're supposed to just accept that every single D&D setting MUST be in line with Planescape lore.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.