I don't personally don't feel that the changes are trivial, since I find that I have a strong preference for the photo over the painting, but that's subjective.
Either way, legally at least, you're right that many places wouldn't consider making artistic changes to be enough. I feel that artists should be free to create new derivative works however. All art is derivative and the purpose of copyright should be to protect artists from unauthorized reproduction, not prevent the creation of new artistic works. Copyright's original goal was to encourage the creation of new works, it's just been twisted over time into something that too often does the opposite of what it was created for.
I agree that it's crazy that they didn't think photo should have any protection under copyright. It shouldn't matter how unoriginal it was, it's still clearly a work of art. It could get a little more complicated when you're talking about a photo of a very common thing (like a popular landmark) where it might be hard to tell the difference between two people's photos of the same thing, but a photo taken of a specific model at a specific time under specific lighting etc. that seems plenty unique enough to me.
Either way, legally at least, you're right that many places wouldn't consider making artistic changes to be enough. I feel that artists should be free to create new derivative works however. All art is derivative and the purpose of copyright should be to protect artists from unauthorized reproduction, not prevent the creation of new artistic works. Copyright's original goal was to encourage the creation of new works, it's just been twisted over time into something that too often does the opposite of what it was created for.
I agree that it's crazy that they didn't think photo should have any protection under copyright. It shouldn't matter how unoriginal it was, it's still clearly a work of art. It could get a little more complicated when you're talking about a photo of a very common thing (like a popular landmark) where it might be hard to tell the difference between two people's photos of the same thing, but a photo taken of a specific model at a specific time under specific lighting etc. that seems plenty unique enough to me.