ES4: Shivering Isles - Interview @ Game Informer

GI: Are there new mounts?

Howard: No. We’re less a fan of the horses than most people.

GI: Why?

Howard: Truthfully, I think they’re nice—people in a game like this want to ride horses. But they probably don’t do everything they could do. They never, for me, got to the final level that I think they could have, as far as how they feel, fighting on them--other things like that. They’re good for quickly riding around the world, and that’s fine. You do, when you play the game, see, “They could do this for the horses, or they could do this for the horses, and it doesn’t.” So, we kept them out of this.