Tracking the status of your cargo. At the moment you always have uncertainity during the voyage - you don't know if e.g. temperature was held consistently until you took control of the cargo after arrival, or if it was tampered with during transit in any way.

For fleet owners, no matter if for ships, cars/trucks or planes, management becomes way easier if they have global high bandwidth data uplink: you can detect stuff like engine or other part wear early by running big data analysis on telemetry, and in disaster case you have way better logs to operate on (both post mortem and during troubleshooting).

This by the way also is relevant for car manufacturers - with the exception of Tesla, the only way classic car manufacturers get information on how their cars are used in the real world comes from test drivers, accident reports and shop visits. Consistent data uplinks allow for a lot more telemetry that can be used to improve their products.

Surprisingly, even scientists can benefit from this - have ships transmit real-time data about air pressure, sunlight, wave height etc. and suddenly you have a global network of floating data buoys.