We already have goblins, yes, but goblins are shown are disorganized war bands that pillage and loot the civilizations. Kobolds, on the other hand, are far more organized in their tactics, their organization, their wit, and lastly, their traps. A kobold civilization could instead be one that in the beginning strives only to protect itself as best as it may with tile traps (improvements) and special buildings in their cities that allow them to survive raids from barbarians and other civs. At the end though, their power could increase tremendously. What do you think?