Same reason I quite randomly posting nude photos of myself - you never know where they will show up!
Seriously, anymore, unless you somehow protect your photos from being copied, people will lift them. That has happened to me a few times. It's at first flattering, then offensive. In an age where copyright is so important, laws are just not enforced so people go with the "I didn't know" bit. I think legally, we would all be out of luck as we seldom protect our pics. I think posting them publicly is in a way seen as giving permission.
I agree it would have been a courteous thing especially since both parties are familiar with each other. People go to great lengths to make nice images and for them to be used implies another is unable to make quality pics even when profit is involved. That's where it becomes offensive IMO.
Great jacket though!
Dave