It's like I said, it depends on how their story shakes down. Is there something cool or unique about their culture that makes them memorable? If not, I at worst don't care if they're playable or not. If so, I'd probably enjoy them being added, because that's one more cool facet for one of the factions. Hell, I'd even just say add them anyway because it would make some people happy, and they certainly aren't out of place in the setting.