I agree... no psykers and you lose an entire element of the story that was vital to the universe. No psykers, no variety, no fun.
So does that mean in order to do anything casterish (such as heal) you're gonna have to play Eldar, cause that would suck.
If they want to keep with the traditional MMO classes then yes - some type of psyker variety will be needed, despite the fact that Imperium psykers aren't necessarily considering "casters" or "magic users", that's more Tzeentch's realm.