This week hasn't been the first time I've seen experienced Wikipedians confuse the difference between republication permission and license release. So at the risk of making this too simple, here's an analogy.
Way back in first grade my crayon box was missing an orange crayon. So when we had a coloring assignment and I needed orange, I asked the girl at the next desk if I could borrow hers. She agreed. When I was done I gave it right back.
The lack of an orange crayon was not an urgent concern to the adults of the surrounding universe, so a couple of days later I asked her and she let me borrow it a second time. This started to become routine. She was quite friendly and always let me borrow her crayon.
Then one day she was away from her desk when I needed the crayon, and rather than walk to the other side of the room and ask yet again I just reached for her supply bin. At this point the teacher intervened and accused me of stealing. I was insulted.
"I'm not stealing. I always use her orange crayon."
"You can't use it unless you get her permission."
"But she always lets me!"
At this point the teacher called to the girl, who immediately granted permission. In addition to the crayon I also got a brief lecture in private property.
She hadn't donated the crayon to me. She hadn't donated it to the whole class. It was still hers and she could keep it for herself if she wanted.
No matter how generous a person or organization is about reuse of their images, the material must be presumed to remain under full copyright unless the owner explicitly changes the license.