What agharta said, and I think Le Guin realized later, and said in print, that the book is weaker because of that motivation.

Also, and this is nit-picky, elsewhere it's said that the Fore-eras of Hain are about one million years ago, not three. But the stories about the Hainish worlds are not all consistent with each other; among other things, Le Guin notes that only the early books include mindspeech.