Fair point. Impressionism was in no small part a reaction to the overly stuffy and formal schools of realistic painting of the time. You've made me think: I wonder how much photography contributed to their frustration with that academic painting style?
But still, painting is painting. Take the Dutch Old Masters: incredibly realistic, lifelike pictures, but also extraordinarily powerful. One doesn't preclude the other, but in every case something about the medium contributes to its power. It might be the fact that a sitter for one of Caravaggio's Christs was actually suffering due to holding his body in place for so long; it could be a need to invent some aspect of light in a scene which ends up illuminating a girl's face in a particularly lovely way.
There's plenty of emotion in photography, too, but it tends to come as a result of skilful use of that medium's own characteristics: spontaneity, completeness, and presence. Press photographs are a great example, exploiting the medium's immediacy to steal a few, shocking milliseconds of reality. That applies even to powerful landscape photographs, in the opposite way: They are very carefully staged, manipulated and contrived, all simply a way to align the limitations of the medium (only 1/500th of a second to make an image) with a particularly beautiful instant of passing space-time.