If the Inner Planes are the foundation of all matter in the 'verse...
And the Outer Planes represent concrete philosophies and ideas...
Does that mean the Outer Planes are mental constructs? Therefore planars have no physical bodies, in the sense that primes do. Sure, an Ysgardian has a body when he's on Ysgard, but if he travels to Acheron, does his body change?
I understand that it doesn't work that way accorind to canon. I'm suggesting it as a variant for a personal campaign. Thoughts?
While I think it would have to be a long-term process (i.e. visiting a different plane for a few day wouldn't change the visiting planars drastically), I think that this idea has promise. Either the plane changes the visitor (causing a gradual "corruption" to the visitor - and perhaps the draining of the Grey Wastes is just the most obvious example of this effect) or the visitor changes the plane (e.g. if there is an infestation of visitors with similar views, they might alter part of the plane but that this in turn would cause that sliver of the plane to shift and relocate itself into a now-more-approprate plane.
To me, this seems like it would add a lot to the "battlefields" of the planes where various explorers/colonists/invaders try to wrest control of plots from one another
Now whether one needs to make the planar a being of "pure thought" is debatable (at least to me)