Including pay the exhorbitant amount of money needed for such a realistic graphical system, I hope.
It's not really about the real-world comparison. We know the animals in TES have souls, because we have a spell that's specifically made to trap them. I'm fairly sure that the reason you couldn't trap human souls before was a missing gameplay mechanic; after all, you could grab Vivec's because the game classified him as a creature. I would find it hard to believe that his soul wasn't at *least* as "special" as a playable humanoid's. We're looking at a fictional world with actual explanations for things on what the stuff of the universe is, where souls come from, where they go, so it doesn't quite fit with a real life comparison. I'd be fine with totally different creatures having different requirements for trapping their soul, but the "this is worse!" feel of suddenly slapping black soul gems on the situation feels like the same enforced morality as things like "necromancers are evil" and "daedra are demons" that also oversimplified things in Oblivion for easier moral consumption.