I think people are confusing the medallion and the app and associating them both together when they are two seperate entities.
I am I agreement that the app is badly designed and even worse, disastrously implemented. It does work better on board but really should be rewritten. I would be ashamed and deservably sacked if I produced a product of this quality.
The medallion itself is a great device, does not need the app to operate and is far superior than a simple key card. Just think about the information it provides Princess and if the location information provided to them is used right, can provide amazing statistical information about popularity of events and people flow throughout the ship. That information alone is worth more than the cost of implementing it fleet wide. This should help in designing future ships as well as aiding decisions on changes what locations onboard should be kept or possibly removed. I am amazed that all other lines have not yet gone to use similar location tracking system, it's only a matter of time.