As [MENTION=607]Klaus[/MENTION] noted, the thematic underpinning of the 4e cosmology is creation: order vs chaos.By trying to redefine demons -the iconic representation of Chaotic Evil- as corrupt elementals, you break rather radically from the thematic dichotomy present in D&D and replace it with a similar dichotomy of Astral Sea versus Elemental Chaos/Abyss but lacking the thematic justification of why it's all there
In this repsect it hearkens back to pre-AD&D D&Disms (themselves derived from pulp and post-pulp fantasy literature). And the tensions between being and becoming also appear fairly prominently in many non-fictional works of religion and philosophy.