For those who have areas with notable details but no maps, I've added the following image to the wiki, along with an "Unmapped Location" category.

Anyone wanting to do a map of an established location can simply click the category and have a list of unmapped locations at their fingertips. You just have to add the category to your wiki pages.

The image is just an attention grabber for those browsing the wiki; if they read something that interests them, maybe they'll want to map it as well, if they know no one is currently working on it.

See Port Magalie for an example.