What is the general goal of the feature?
To reduce tampering of the pictures attached with the forms.
What are some example use cases for this feature?
This is valid for the cases of field visits, something like quality monitoring, school inspection, etc.
The GPS co-ords pulling should be paired with the picture question by default. This is to counter the situation that a form has pictures but does not have location question. So, the picture question should have its own co-ords feature.
Most of the Android devices I've seen have a setting that allows GPS/location to be embedded in the camera image. And if your camera app doesn't support that (or your processing pipeline can't extract that data), you can add a GPS question to the form. Is there a reason why that approach wouldn't work?
Just saw a suggestion at ODK Best Practices that might be useful.
For additional audit-ability, use OpenCamera with a custom text, timestamp, and gps stamp embedded into the photo. For those stuck on older Collect versions, it also compresses photos to reduce bandwidth.