A couple of comments on this thread from long ago:
1. MacKenzie was not the only architect to go on record as Pine Valley not being the ideal course. The foreword to Wethered and Simpson's book has a little snippet about Pine Valley that is anything but complimentary. Bernard Darwin, too, remarked that he thought "the right of eternal punishment should be reserved for a higher authority." Note that Pine Valley is hard now, but it was wicked hard by the standards of the 1920's.
2. GOLF DIGEST does ask its panelists to rate courses in terms of playability, but they do not use playability scores as a factor in their rankings of the 100 Greatest Courses -- they only use it for their rankings of new courses, public courses, and resort courses. If they did use it as a factor, perhaps Pine Valley would not be #1 ... although, knowing the way GOLF DIGEST panelists vote, they probably find a way to rationalize a 7 or an 8 for it on Playability, too. [I don't know what their definition of Playability is.]
3. My own definition of playability is to what extent weaker golfers are able to get around the course. An old MacKenzie quote used the phrase "irrespective of piling up a big score," and I'm kind of on the same page there ... I don't require the 100-shooter to get around in 90, which would rarely happen even if a course had no hazards, and I don't mind if there are some hazards that are death traps for him or her. I just don't want to see a lot of forced carries -- especially carries of the length that short hitters have to lay up to the near edge of them, and then still struggle to get over -- or fairways so narrow and rough so severe that recovery shots from bad drives are often played sideways.