I think it would be interesting to see sub factions and not just one gigantic stereotypical group. Just cause your an Orc for example doesn't mean your going to go with the collective. Based of ideology, politics or many other ideas. It would give the chance for more lore to occur and the ability to expand on factions/concepts or even tolerance between various factions. You could even play into some plot where various members of said factions formed a coalition of some kind to fight a growing superpower that was threatening the way of life for another faction or number of them.