Heya!

This is a wonderful idea! You can't know a place if you don't have its map, no matter what. You'll be able to have your place's map afterall.
This depends on how FFXIV Dev Team described their definition of Adventurer in the game, if he's one that just got in a place without knowing anything, or simply someone who likes to wander around the world and has an updated map of every place.

I would find it great if they could implement Maps by the vendors. They don't keep place in the inventory, just like books or skills, and will give a better immersion in the game, because you had to Buy the map in order to visit a place. If you didn't buy a map, you would simply freak out and end nowhere. Also, every vendor has only the maps of the other fields than the ones of your city-state, because you'll receive that map by the first quest dude.

If this will not be possible, I hope that dungeons will have to get you buy a map =)

See ya!