If you use matplotlib, it needs at least 8MB of libraries and if you use cartopy, it also needs matplotlib, so the gramps package will grow aproximately 16MB for windows and mac users.
It’s difficult to add more libraries to gramps.
The gramps package is already very big. (100MB for Macs and 65MB for Windows)
Linux is better managed for that.
matplotlib uses its own maps.
cartopy can use some other maps (stamen, osm, google …),