Sean:
It is, of course, a much different question in the UK, where there are no "cart courses" and the question is only about the degree of difficulty of the walk. I think Jason's original premise is about courses that are designed to be played out of carts, and don't really consider the walker. There are many of those in the US, and many of them on sites where it was certainly possible to have built a walkable course instead, but the people with the $$$ wanted it different, usually because of real estate interests.
In some sense, this debate is similar to the one that used to go on here a lot -- whether it was possible to have a great course as part of a housing development. There are some people rating for the magazines who put a -10 on the card when a course is part of a development, because they don't like the idea of homes intruding on the course. Again, that's a black and white way of looking at it, and even the fiercest opponents of "development golf" just ignore that many great courses [Merion, Pine Valley] have homes on the outside, and that some [St. George's Hill, Muirfield Village] were built around housing. And again, as with the golf cart argument, they ignore the economic reality, which is that many courses wouldn't be built at all if it hadn't been for the housing.