I skimmed this again this morning, and agree with the point that the compact course is dead, but no one has mentioned the single most important and pedantic reason.....
Every type of construction is bigger - roads are wider, homes bigger, etc. There is some reaction to that trend now. Am just moving into a new planned community, and entry roads are kept narrow to reduce speed, etc. Housing lots are reduced (no more lawn mowing! yay for me!)
In golf, compactness went away due to extra length, discussed, but also the learned need for bigger safety margins. I think most are talking walkable and compact, really meaning the next tee right off the previous green. Some of the green/next tee center point separations on old courses is less than 100 feet. Originally, at TOC, they were zero feet, but that soon proved impractical.
As a real world number, I recall my first project for KN - parallel greens and tees we strove for 175 feet, and accepted 160 feet. Later, our, then my standard was 200 feet perhaps influenced by those plastic golf holes use as templates for routing, but really, for safety and fitting cart path in between reasons. But, I would accept 175 on hook to hook sides. I recall one at 145 feet between centerlines, typical on many Ross courses, but when laid out in the field, the hair stood up on my neck, a good indicator of when things are too close!
In more recent years, 200 on parallel holes is still good minimum, with 225-250 at LZ points, more preferred. However, I realized how few shots go over the green, and am more than willing to put a tee as low as 150 foot from the back of the previous green center in many cases, still more than Ross, etc., but, given greens and tees complexes are larger these days too, pretty reasonable and reasonably close.
Cart paths, safety, circulation, maybe even just a general preference for bigger scale in society all have driven greens and tees apart a little bit.