I learn from both types of occasions. Kodiak has a blurb on his profile, "edit is OK... always want to learn!" That is exactly the way that I feel about my images.
Regarding doing additional PP on member's images, it is often easier to show a suggestion as an image than try to verbally explain where I am coming from!
I wonder if most of our members feel this way? Perhaps if a few persons don't want any additional PP posted for their images, they should mention so. OTOH, maybe it would be a good idea for me and for other people who feel like I do about critiques to follow Kodiak's lead and announce that it is OK to edit images!