Except when you can't: when I was going with my friends to Japan they couldn't download the maps due to a licensing issue or something.
Luckily OSM was more than happy to let me download it's maps.
This used to be an issue, but downloading maps of Japan is possible these days.
Hit the same thing in China. I have free cellular data while there--but at a trickle. Maps were painful and the VPN needed to access Google Maps also added it's own headaches because of the spotty connection causing repeated reconnects.