User blog comment:Supahbadmarine/Canon Discussion 3:THe Warp, Chaos and Gods/@comment-4964060-20131117165030

Ugh, Chaos Gods have always been a topic of nonstop debate on this site. The main problem with them is that a God must represent some kind of emotion, and since their aren't that many emotions out there, we are limited in the number of Chaos Gods we can have.

http://en.wikipedia.org/wiki/Emotion the little infobox to the right gives you a list of emotions, and even then some are just stronger (or less so) than others. Honestly, while I'm not against Chaos Gods, it's just so much more limited then say, the amount of Space Marine Chapters or Imperial Guard Regiments one can create.