But he is necessary to the story. He had to be there to save Rand 3 times or Rand would have failed, according to Min's vision.

One of the recurring themes in the books is characters who don't have the needed epiphany that resolves whatever internal conflict that's hindering them until the most critical moment. With Perrin, he doesn't break through his final walls until the climactic battles with Slayer. I hope whatever motivation they invented doesn't eliminate the arc to his acceptance of being a wolf brother.