I agree with your point, and I am not a historian of bunker sand, but my guess is that as the most known and viewed course in the US, ANGC had a sizable impact on bunker sand.
I have a minor in the history of bunker sand.
Up through the 1980's, nearly all courses sourced bunker sand from the nearest quarry. There were some guidelines as to the best range of particle sizes, but clubs took what they could get. The 'river sand' Jim Hoak describes was common in Texas and Oklahoma.
In the 1990's it started to change. Jack Nicklaus was building courses all around the country, and decided that the sand he'd gotten for some projects in the Midwest - from the Best Sand Company outside of Cleveland - was the best quality he'd seen, so he started specifying it for courses as far south as Florida. Tom Fazio actually built a course adjacent to the Best Sand quarry, and he started specifying it everywhere, too. And naturally every other club who wanted the best conditions followed.
PGA TOUR players have always wanted for conditions to be as consistent as possible from week to week, so they don't have to adjust their games to different green speeds, different bunker sand, etc. In the 80's they experimented with wetting agents and other techniques to get the sand at outlier courses to be more consistent -- I did an article for GOLF Magazine about that, and interviewed David Eger, who was the setup man for the Tour at that time. David said he spent more time and brain damage working on the bunker sand at clubs than any other topic. Eventually, the Tour also started recommending replacing all the bunker sand with the best material possible. The fact that it also made bunker play easier for the pros was just a side effect.
* NOTE that not everyone follows along. Many of the clubs where we have done restorations insist on using the most expensive bunker sand they can find. However at places like Sand Hills, Pacific Dunes, Barnbougle, and Sand Valley, you are playing out of the sand that we exposed when the bunker was dug -- unless they've had to fill the bunker back up from a nearby pit because of wind erosion!