The Salt of the Earth
As for Wenders, I much prefer his fictional works over his documentaries, which are (as far as I can recall) all works of a fan for a fellow artist. He hides himself to put the subject front and center, in this case photographer Sebastião Salgado. While this kind of art is all subject to the viewer, Wenders does a great job conveying Salgado's talent, backed up by hundreds of pictures. I wish more time was spent on the wife, who seems a key piece of guidance and support for Salgado, and the turn towards nature photography doesn't get pressed for a satisfying explanation, though the results are just as good. (It even contradicts the title of the film.) Overall, I liked it, but I don't see what makes it an exceptional documentary.
I too prefer his fictional works over his docs. Pina, Buena Vista Social Club, Tokyo-Ga they're good, and in the last I even had preexisting interest in the subject (if you haven't seen it it might be a nice cap to your Ozu exploration if you make it to the end), but they're not exceptional to me in the way Alice in the Cities, Kings of The Road, Paris, Texas or Wings of Desire are (I need to see more now that I'm looking through his filmography).
So why this one? I didn't write a review when I watched it a year or so ago but I think I remember, and maybe it ties to the discussion above from Timbuktu. What you wrote is a good starting point. The film conveys Salgado's talent really well and so we get not only to enjoy learning about a bunch of things, but we get to appreciate his wonderful photography. And I do agree that more time on his wife would be appreciated. But if this was just a film about an interesting man with an interesting life it wouldn't be on my list (or maybe it would, I dunno, Salgado's life is really interesting). What makes it stand out for me are three things. The first is Salgado's life of travel and exile (of sorts). While the specifics of his life are, obviously, alien to me the generalities, especially from an emotional perspective, hit close. I see parts of me in him and parts of my parents and their experiences and choices and while that's a small part of the film it was definitely something that gave me an entry point to connect with it. The second is the amazing photographs. They are captivating and haunting and insightful. They show us the world and a slice of its turmoil, its humanity and its inhumanity. They are incisive in the way they show us not just the world and its people, but they show us so much that isn't in the pictures, the causal events and circumstances that lead thousands to a mine or to death on a road to nowhere. It's insight into the diversity of human experiences that, much like in Timbuktu, feeds my desire for exploration and knowledge and provides path for me to consider my place in this world. My own good luck and my misfortunes, a view outside my own little world, and even the slightly wider but still constrained view of the western world into the wider human experience.
But the key to the film, the thing that makes it so powerful for me, is the way it interweaves those two things. It isn't just a film about a photographer, it isn't just a film about downtrodden people in the world, it's a film about the interaction and intersection of the two. It's about Salgado exploring the same questions I'm exploring without trying to give me a trite or easy answer. The photography is given context that gives it another layer of meaning, so that it's not just the subjects in the photographs we consider, but the photographer and how he got there and what he sees and what he thinks of what he's seeing and what he's doing. And it's messy. It's tough to watch sometimes and it eats at you, the way it should eat at all of us that this is the reality of the world we live in. I don't recall how much the turn towards nature photography is explicitly explained in the film, but I never felt it needed more pressing because it seemed so obvious to me. Humanity broke his soul. There's only so much misery and death one can witness, and eventually whatever small part we feel we're doing feels overwhelmingly inadequate. The life he was leading was increasingly hard to live, because of age, because of familial constraints and, more than anything, because the subject matter became too much and witnessing and documenting no longer felt like enough. Artistically the result is, as you say, just as good, but it's once again the interaction between the photos and the photographer that is the key. And in this final chapter the photographer is not just documenting the actions of others, he's documenting something he's doing himself and connecting the people and the earth. As a saying "salt of the earth" may represent the people, but the final chapter puts an emphasis on the "earth" part. It's not a contradiction of the title, it's a recontextualization of it. A reminder that not only are we of this earth, this earth is also of us.