I personally think that the use of AI for fantasy mapping is a mixture of being both fun and questionable - on one hand, I think that you can have a lot of fun with AI in that it helps to simplify the generation of basic outlines for landmasses, and it can be a useful tool to start off with for a beginner who might not know how to fumble around with generating clouds in GIMP to get the ideal landmass shapes for instance, or to highlight some of the examples from previous posters about generating more complex icons that someone could put on a map. But on the other hand, I also believe that when you do a whole project with AI, you are not quite putting in the effort yourself, as you have no control over where you would like to place towns, mountainous terrains and rivers etc - when I like to make fantasy maps, I prefer to have some kind of control over where I would like to put the various features that define the landmass onto the map.

Although I am looking forward to seeing some AI tool for fantasy mapping that strikes a perfectly good balance between originality and simplicity.