This was one of my favorite things to find in a book, when I was still a kid-reader. I love maps, especially completely fictional ones.
I drew so, so many of my own, for what would have been a fictional planet's worth of imagined places, when I was a kid. What is it about maps? I don't know. They're like a list of possibilities, a whole catalogue of places I haven't been...yet.
And as a writer who often uses completely fictional settings, I've found having some kind of very rough map is vital to keeping it all in order, and achieving coherency, when my characters are running all over the globe, or even just all over town.