Unfortunately the SD card use case doesn’t sound so simple to me, given we can’t assume there’s a particular folder structure on the SD card.
I can see that adding the option to exclude particular folders would work better for you, but this would definitely require additional design and implementation work. I’m not saying it’s a bad idea, but it’s not going to be an immediate fix for you I’m afraid.
I originally started looking at this because you raised it as a topic for the community meeting on Thursday. Are you still interested in it being discussed there?