Greetings Anthony.
Okay, second question first. As mentioned in the interview, the primary criterion for selection was the 1,000 clubs that might be most interesting to potential visitors, not any sort of "1,000 best." In that context, there are a fair number of courses that acquisitive golfers may be curious about - often due to tournament or architectural histories - that I thus deemed worthy of inclusion even if they're not among the game's architectural greats (hence the 2s and 2.5s). It's true, of course, that with so many strong courses to choose from, I didn't select many on history alone, thus the absence of 1s and 1.5s. This may seem odd strictly within the context of this volume, but will make more big-picture sense after the resort book (which covers virtually every U.S. resort and thus has plenty of low numbers) comes out.
So far as the five diamond scale goes, the purpose was to create some sort of relative measuring device that was not about my personal opinion (which few people would - or should - care about anyway) - a rating that measures, in effect, how prestigious a feather in one's golfing cap the playing of a particular layout may be. It is inevitable, I suppose, that many readers will continue to see any sort of numerical rating as being representative strictly of design quality even though the introduction pretty clearly states otherwise; I suspect this is something that we're all semi-conditioned to. But the example I generally offer is Champions, whose courses would hold little playing appeal to me and do not, in my personal view, represent any sort of great design. But with Jack Burke and Jimmy Demaret, and a U.S. Open, and several Tour Championships, and Ben Hogan's final PGA Tour round, etc., and with the unique cachet that the club holds in Houston, Champions remains a very prestigious place to play (even if only to meet Jackie Burke). Thus it gets four diamonds - though clearly not because its courses rate among the genuine elite.
Having said all of that, quality of design is the primary component in the prestige associated with many clubs, and that's fine; indeed, I factored it in heavily - but based upon published rankings and commentaries (whether I agree with them or not) and the privately expressed opinions of several learned people whose opinions I trust. Therefore, if you view the ratings in what might be called a "prestige" sense, they'll generally make sense (or so the great majority of my early feedback suggests). If, however, one ignores the introductory explanation and instead interprets them as a quality rating (e.g., an alternative to Tom Doak's 1-10 scale), then a fair number of entries probably won't make sense, because that's not what the rating is designed to be about.
Final point: Though participants (and readers) on this website represent an audience for whom a book like this figures to hold obvious interest, they're not, in many ways, who the book (and its sisters) is really written for. GCA types tend to be well-traveled and a bit more knowledgeable than the "average" golfer - enough so, in fact, that a book like this may only hold entertainment value (one hopes...) for a great many of them. But there are several million less knowledgeable/experienced golfers out there with the potential to access some of these clubs (and many millions who can play the resort and public courses) and the value of these books will, I suspect, be considerably higher for them.
But we'll see.
DW