If you have fun with worldbuilding in your stories, maps are great. When you’re stuck for ideas, often starting from the landscape up can help.
Also, shifting your brain into a different area of creativity (drawing instead of writing) can loosen up the ideas. So draw a hand-made map!
If nothing else, it can help you keep track of which direction your characters are going and what they’re going to encounter next. It can help you keep your mind on terrain and environment, remind you to do good descriptions.
And most of all, it’s fun!