I've recently had the occasion to, yet again, reflect on the work and career of Ian McHarg. This time I stumbled onto the NY Times obituary from his death in 2001. If you doubt his impact, just note how long the obit is, in the paper of record. I count it at 1,100 words, which is substantial.
The obituary paints him as a grand thinker and a dreamer. Niall Kirkwood reflected that, "The last thing he said to me, last April or so, was, `I want to do this big study, a geophysical inventory for the whole globe, the world,'" Mr. Kirkwood said. "He was still dreaming far beyond his circumstances." It also pointed out the costs of dreaming, quoting him as saying that "it might just be possible now to avoid dying bankrupt."
But it is also interesting to note that it doesn't talk about his use of overlays or influence on GIS. Admittedly, it was a newspaper obit and not one from a planning journal. But it may be as telling.