Say your luggage is misrouted or mishandled. Does knowing the GPS coordinates actually help? In the end you still need to get the airline / airport to properly process and return the luggage. I somehow don't imagine that there exists a process now to get that information to the right places. Knowing that your luggage is stuck in London when you're in Tokyo doesn't really un-ruin your vacation, so I'm not sure about how that aspect is being marketed.