Previously we could just see the pic of map. With Kartographer extension, now we can navigate map via latitude, longitude and zoom.
It would be much better to allow navigation through time as well.
Use-cases are limitless, most prominent being historical articles about empires. They span over hundreds of years and their area vary drastically. If we want to depict extent of empire through various years, we had to use multiple pics. With Kartographer, that could be upgraded.