One for Sorrow

Exactly! What's the point of a redemption plot if you didn't do anything to be redeemed from in the first place. In my view, it makes Draco/Regulus/probably Snape a greater character to have deliberately gone down the wrong path and then have the strength to say "This is enough." Harry, for example, hasn't stopped throwing Crucio at people yet. He has not looked into himself and found the moral strength to not lash out at people he hates. Draco has, finally, done this.