The Imperium is notoriously xenophobic, like the Empire x10000. I would imagine the Imperium would partner with the Empire to exterminate (not enslave) all alien species and then incorporate the Empire into the Imperium. Alien force users would be exterminated while human force users would be taken by the Black Ships to further server the true Emporer who sits on the Golden Throne.

I think quality story is important for the RPG aspect of MMORPG's. Therefore, I say yes. I have found myself more immersed in this games environment then any other MMO's that I've played, and I'm not even on an RPG server. If I wanted no story, no substance, simply grinding lvls in hours so I could stand around the main social hub waiting to que for the next round of purple pixels I'd play that other MMO.