Board Thread:Warhammer 40k General Discussion/@comment-6078851-20130318203252/@comment-7186329-20130403155021

That began to happen, the Chaos gods began losing major power. They even foresaw how weakened they would become, and probably even wither away. That lead to the desperate move of creating a Warp storm in the laboratory itself. To scatter the primarchs required a lot of combined effort from all of the Chaos gods. They were severly weakend.

The chaos gods do incorporate some positive aspects, they are not completely from negative emotion. If The Emperor removed as much suffering and hate from the Imperium, and He did, that would weaken the Chaos gods, or even possible make them less `chaos`-e.