"I believe Crump left the pimple intact and wrote about replacing it with a contoured ridge running through the green."
Pat:
George Crump really didn't write much of anything about Pine Valley. He was interviewed some but the record of his thoughts about Pine Valley and the details of what he wanted to do and planned to do pretty much comes from his two closest friends there, Father Simon Carr and William Poultney Smith, two excellent players. I call those hole by hole accounts by those two men of what Crump wanted to do, "the remembrances". I believe the 1921 Advisory Committee asked them to write those "remembrances" so they'd have a better idea how to finish the course the way Crump wanted it after he died. Both of them said why Crump put that "pimple" on #18, what he was trying to accomplish with it and that he considered it to be temporary until he could work out a better feature (they both mentioned he was thinking of a slight ridge running from the "pimple's" position to the right edge of the green). There was a lot of features on that course that Crump considered temporary until he could go back and fix them. Some of those features he may've considered temporary still remains and some of them were removed by Alison and the 1921 Advisory Committee. Things like a form of Mid-Surrey mounding near the first green and around the rear of the third green. Crump wanted to change the 6th green and its position, the seventh hole, the 9th, the 11th and the 16th. A few other of his original greens were too radical and were changed early on such as greens #6, 7, 8, 9, 11, 17, and of course the "pimple" on #18.
"The question is, why hasn't it been restored or reintroduced as a ridge as Crump indicated."
That's a good question. I'm not sure how aware the club has ever been of some of the foregoing and those details.
"My gut reaction is because so few people even know about it, and who removed it, and what Crump wanted in its place."
Pretty much everyone who knows the architecture of PVGC knows John Arthur Brown removed that "Pimple". They know why too----eg like some of the other early stuff that was changed early on was just very controversial---considered far too radical. There's no question at all that's the way that "pimple" on #18 green was looked at.
"Something needs to be done, whether it's a pimple or a ridge, the green needs interesting contouring to heighten the challenge on the approach, recovery and putt."
I wouldn't disagree with that particularly given Crump's specific thoughts on the subject are very much there in the archives in enough detail.