An all-natural, strike indicator will definitely help a fly fishing novice catch more fish on nymphs and puts another tool at the disposal of the intermediate or expert nymph fisher.
When is a strike indicator needed? When fishing deeper water in long runs it might be the only way to keep contact with your flies and for deep water angling weight is usually used which can pull the tip of the line under the surface. When this happens you lose contact with you whole system. This is a good time to apply an indicator in the terminal system.