I find the OP's position to be too broad. People learn in different ways for different reasons. Teachers teach in different ways. In some ways digital can be a better tool for learning...especially if the teacher dwells on the image and not the technical aspects. If an image was taken that was not well seen, then the teacher can point this out and ask the student to re-take the image...not just try to "fix" it in PS.

The teacher can require that the images be uncropped (or at least not cropped in one dimension) to improve the students' seeing. The use of color as a compositional element is not something one can "fix" in PS...The tool provides much instruction, but in the end it is the teacher who teaches.