Opinions vary widely on whether this is "worth it." Some users refuse to pay. Some prefer OneDrive or other cloud storage options. Some find Apple's 50 GB option to be "absurdly cheap" and happily pay for it. The author of the article (link above) purchased the 200 GB storage plan to back up valuable photos and videos so he doesn't have to carry them on his iPhone and iPad.
So the answer is a personal one based on your backup strategy (e.g., for photos), the amount of data you want to store, and your budget.