Playing devils advocate here...turn the tables for a minute, to help clarify the situation:
I am aware that the photogs own their works, but is there a time limit?
How long do you as an artist own your work? Why should it be different for a photographer?
Regarding modifying the photo...
What if a photographer took a photo of your art, then via darkroom or digital manipulation, made many changes to it, color, values, even distorting the image or combining it with others? Do you think this would be ok?