I think it is because of their sense of history
Hopefully they are personal expression of their owner.
If you ever take a great vacation, picking up a map of the area (or island if you are lucky enough) can be an amazing souvenir and putting it up on your wall will make your house tell part of your story.
I also love the huge scale of world and US maps that were once used in schools.
Using maps of the area is a great idea for a vacation rental home or in a guest room.
So are you a fan?