Kevin,
To answer your question, I believe that "short" par 3's went out of vogue, with the long, back breaking par 3 taking their place.
On a number of modern courses I've played, 210-230 par 3's are far more prevalent than short, 120-140 par 3's
Perhaps, with TV, Palmer, Nicklaus, Weiskopf and other long hitters, short par 3's were viewed as an insufficient challenge, hence the trend veered
toward longer holes