Seems to me things have gotten confused.
MacK's pitch about economy was not that less is cheaper. His pitch was not that people ought to build fewer bunkers, smaller greens, narrower mowed areas, and use less shaping.
His pitch was that better design up front will save you money in the long run. Ergo, hire me. You frequently hear the same pitch today. Indeed, it is now a marketing cliche.
I know of no passage by MacK where he states that fewer bunkers should be used because that will make things cheaper for the club. He gave very different reasons for minimizing bunkers. I think he came to those ideas by way of Behr, Simpson, Crane (as someone with a design theory he opposed) and, of course, by way of his own innate intelligence.
You don't build a course like ANGC with enormous mowed areas if you are worried much about saving money. You don't build gigantic greens if you are worried about economy. You don't design wild (wild is not meant metaphorically here) contouring in and around greens if you are worried much about saving a buck. You don't pipe creeks, reroute creeks, create ponds and lakes if a major design goal was to save money.
MacK's writings on the subject are quite clear. As for dates, no one, from John Maynard Keynes to your Uncle Ed had any idea in 1929 or 1930 of the depth and duration of the Depression that was to ensue.
Ron Whitten's theory of the design at ANGC commits the classic "whiggism" fallacy. Which is, because we know now (some 80 years later) how bad the Depression turned out, we project that knowledge to people as they were living its first years. Things were very bad in 1931. But Ron Whitten projects onto people alive in 1931 the knowledge we now have that things were going to get much, much worse and stay that way for a very long time. People at the time thought things would turn around, as they always had. Golf architecture didn't shift into survival mode until later.
Bob