The ability to lift not only unconscious hearthlings, but conscious ones would be neat, though given the nature of the ordeal you should only be allowed to do so with the Theft skill (Or a new Kidnapping skill that leaves scents even longer than Murder? As well as preventing hearthing home.)
The most desired reason for this is saving allies who are drowning, it doesn't seem right that we can only sit and watch as they drain stamina and suffocate on water where we could be dragging them to safety/land/boats.
The other reason is the added aspect of possibly kidnapping people/holding them at a place for whatever purposes are desired (Though, in this case to prevent trolling it might be desireable to add a way to hearthlings to suicide).