No matter how much anesthesia the anesthesiologist applies during surgery, afterwards one must always deal with the pain. Now imagine what that pain would be like if the surgery occurred with no drugs. Just the thought of that brings pain, does it not.
Surgery is also always precise and specific dealing with the areas that are causing the body to not function properly. We can be thankful it is because otherwise we could be missing the wrong part of our body or the wrong part could be operated on. Have you ever thought of God as a surgeon making cuts?