I was introduced to Meyer's/Disfarmer's work by a colleague about a year ago. Unfortunately I was told the story about his name and his reclusive nature before I saw his work, so I'm afraid that may have influenced my initial reaction to it, which was far from positive! It would have been better not to know that detail, and to see his work beside the kinds of portrait work that were popular at the time.
Not knowing what his contemporaries were doing at the time, I can't speculate on how innovative he really was. I suppose the most favourable take on his work is that he independently invented modernist portrait minimalism. His approach might come across as straight-ahead, conservative and dull now... but placed in historical context, I suppose that he specifically worked to reject the prevailing American portrait style, which (I guess) still consisted of heavily romanticized, idyllic studio scenes that gave no real insight into the lives of the subjects. He seems to have deconstructed that style.
What I find interesting are the few portraits in which the expression on the faces of the subjects shines through the rigid compositional style.
I do find it ironic that he changed his name; I think the plain, undressed honesty of the rural farm landscape is evident on the face of every single one of his portrait subjects. Why flee that?