I feel bad with the Blight Kings... When I get around to doing my Chaos, I kind of want to include them because they look cool, and the concept is neat. But then I think about how they're based, and not being Monstrous Infantry means you don't full supporting attacks from a second rank, and even one rank is something like 230 points with command, and if they end up in front of Karl Franz Ascendant, they're just a tasty snack. Against a lot of things they're pretty strong though.
Rule of Cool might win out there. But other things like Warrior Chariots are competing in that same category, and the army can only take some much "Cool" before imploding. :-P