It seems my memory mixed this up a bit; the comment refers to Disneyland MK. I imagine it holds true for WDW as well; keep in mind EPCOT design, too. It was first brought to my attention many years ago by a geography professor (ETA:~2007) when we were looking at planned cities. Here is a link and excerpt though via WDFM:
http://www.waltdisney.org/blog/anniversary-day
The success of Disneyland impressed Developer James W. Rouse sufficiently to state in his keynote speech before the 1963 Urban Design Conference at Harvard University, “that the greatest piece of urban design in the United States today is Disneyland. If you think about Disneyland and think of its performance in relationship to its purpose, it’s meaning to people—more than that, it’s meaning to the process of development—you will find it the outstanding piece of urban design in the United States. It took an area of activity—the amusement park—and lifted it to a standard so high in its performance, in its respect for people, in its functioning for people, that it really does become a brand new thing.”
Unfortunately the one area Walt did not have any design control over was the land surrounding his Magic Kingdom.
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I also think that there were similar comments/studies made in 1972 after WDW opened. I would have to do some searching though.