Corey, it's my understanding that three things happened at Pinehurst to lead to greens whose surfaces are about two feet higher than Ross built:
-sand used for very aggressive top-dressing built up the height of the green and naturally caused more to aggregate in the center, thus the dome (sand around the edge tends to fall, wash or blow off)
-sand from bunkers accumulated, causing more diverse patterns (clearly visible today on many holes)
-during mid-1980's "restoration," the attempt to recreate the already altered surfaces led to a construction process where the edges collapsed marginally, further exacerbating the "angle cake" pop-up quality of the greens
Today, only 30 percent of the average 6,000 square foot putting surfaces are under three percent slope, meaning that at modern mowing heights there are precious few hole placements available and very little room for the ball to come to rest. That's why golf there is so tough - the ball doesn;'t stop rolling. But that's a function of excessive slope and excessive green speed beyond anything Ross had anticipated