Not sure exactly what your point is. If your trying to argue that resources were stretched thin because of the number.. I am not buying it. You might have noticed that many of the actors voices are used by multiple npcs. So it wouldn't have been to painful to get extra dialog.
Now think of these 12 npcs. It is unlikely they share a voice actor, because it'd be *really* noticeable. So 12 unique lines of dialog for events.. Possible interactions between followers... That's a fairly intensive workload.
Heck, I am racking my brain, and I can't think of a single western pc game that has 12 voiced character companions that have depth. And if someone suggests DA 3, there is a special spot in the Apocalypse for you.
Lastly, don't get me wrong, I hope they do make the characters right, I just am not betting on them having a companion with the depth of Vilja or Willow (Modded companions for skyrim,fallout nv)