I'm with Hicks on this. Why would Predators have only one body-type. Think of the Ancient Romans when they fought the Germans - the Germans were MASSIVE compared to the legionaries, they had a different language, different fighting style, different culture, different climate... different everything.
The black predators were a great idea and, in all honesty, I didn't think the execution was bad at all. I liked how they hunted as team, they all had their jobs and there was one leader - it was good. Whether they get carried over to IV remains to be seen - but as we know - its officially a sequel.