The media mapper addon is too limited in matching filenames to products. There should be an extension point where developers can add a custom product matcher.
Filename should be passed as parameter and product/variant matched together with info on property or display image where the image should connect should be returned from the matching method.
In our case, customer receives product images named by EAN code, so they would of course like to map files using another (custom) field rather than article number.
I agree with Mårten on this.
The product matcher should also allow multiple products to be identified so that a single image can be connected to multiple products