Here's my scenario: automated georeferencing for aerial photograpy. I get the ground geographical coordinates from the plane's sensors and I need to associate them with the center of the photo in the stitched panorama. Since the processed photo is warped and rotated, we're talking about a centroid computed from the alpha channel. Most of the export formats in APG output a cropped image with no positioning information so they cannot be used. PSD and PSB do the same, but with the "embed all outputs" option they position the images correctly in individual layers.
I can't process the PSB file on Linux because both psdparse and imagemagick fail to handle it, so I'm left with the PSD which due to format limitations can't hold the entire panorama, so I'm getting my centroids from a panorama that's 10% of the maximum size, thus increasing the error margin. BTW, the fact that the automated panorama cropping cuts some of the corners doesn't help either.
The enhancement I propose is the ability to export uncropped pictures in formats supporting transparency and high resolutions like TIFF and PNG.
If I remember well the tiff format, when doing tiff rendering with image output as individual file, we patch the tiff offset metadata to fit in the right position. This may be the information you need that you cannot retried through psd parsing.