This is as diverse as it gets on the back of a motorcycle. Unless you have a different passenger every week.
An adjustable luggage carrier is a useful and safe alternative to a rarely used top case. It creates a spacious and stable platform at the rear of the bike, which can adapt to the circumstances.
The adjustability is more than a gimmick. It allows you to carry large volumes and ride off minutes after delivery, without lugging around a now superfluous top case.