Thanks to Professor Tolkien, the majority of fantasy books have a map somewhere in their pages. It’s often at the front, though some have it in the back. The Belgariad has maps throughout, highlighting the next major location.
So, the title question: Do we really need a map?
Many see it as a given or a necessary resource. Does a story really need this device? Shouldn’t the prose be enough?
Absolutely, the needs of a particular story determine what the answer would be. What’s your answer?