Abstract art has existed for, well, for a long time. It doesn't really matter how long. Ambiguous art has existed probably longer. What did the artist mean that figure to be conveying, on that wall in Lascaux?
The point, or at any rate one point, of the abstract and the ambiguous in art is that it stimulates the imagination. We project our own ideas onto what we see, we imagine shapes in the abstract forms, we imagine stories and thoughts for Mona Lisa. We fill in the missing from our imaginations, fueled by our history and our own ideas.
Photography brings something genuinely new and different to this context. Behind a photograph there is, we believe, an single objective reality. A painting of a woman with an ambiguous smile might or might not accurately represent a real woman with an ambiguous expression. A photograph of a woman with an ambiguous smile represents a definite moment in time when there was a real woman, who really had that smile, and who was thinking some real thoughts and experiencing real emotions at that instant in time.
A genuine abstract also generates an imaginative response. A Mondrian or a Pollock, if you can get past the "what the hell is that thing?" response, will typically get the imagination going a bit, at some level. We're pattern-seeking animals, you'll probably seek some patterns and try to make sense of the piece. You might see something, you might not. You might start thinking about what you don't see. Again, a photograph brings something genuinely new and different here: there is an objective reality. An abstract photograph is a photograph of something, and you can, at least, wonder what the something was, where it was, and what its story is.
Even a clearly staged ambiguous photograph partakes, if only at a remove, of this increased sense of reality. While the man is clearly just posing with some accessories, those accessories are nonetheless real, the man is real and is thinking real thoughts (albeit possibly of the "when do I get paid for this?" variety). The ambiguity might be staged, but there is still a strong sense of reality floating around.
Abstraction and Ambiguity open the door to the imagination. In a photograph they do so in a more compelling way.
This is the important part: Don't let me down.
Don't open the door to my imagination, and then permit that imagination to speculate only on trivialities. Don't make me wonder if that man walking down the street is a Banker or a Venture Capitalist. Give me something bigger and more dramatic to imagine. Let me fill in a good story, not a crummy one. Give me choices, dramatic and interesting choices, but not too many. A macro photograph which could be anything at all is too open ended. Don't tease me with a photograph that could be steel siding or vinyl!!!!
Let me imagine that the man is on his way to kill a friend, or rob a bank, or pay a debt, but make me understand that he's on his way to something big. Let me imagine that she is sad because she had to fire her lover, or because her house has burned, but make me know that her emotions are roiling.
Open the door to my imagination, and give me a big space and interesting space to roam, but don't make me do all the work.