not have the Eagles do that, but since that's not what happened in the story, I think that helped one of the main themes in retaining some of its power.
While others bravely and openly fought evil head to head in a effort to keep it at bay, the two small hobbits bravely and unseen sought to seek evil's complete destruction while enduring great struggle.
So to in our lives. There are times to meet evil head on in view and prevent its spread, but to truly defeat it, it takes the small things that often happen unseen to others and is a more personal struggle.