Some speculation on why Ross's suggested changes at Seaview were largely never accomplished...
Ross was brought in April/May 1915, shortly after Geist hired both Wilfred Reid as professional and Wiliam Connellan as superintendent. Tillinghast speculated that the combination of Ross and Reid's ideas would be used to "stiffen" the course, as many in PHiladelphia were all about making tough golf courses at that time (although that was never the original intent at Seaview).
Geist had already spent way over budget on this project, which was to originally open in 1914, but due to problems with fill in the swampy areas, was delayed until winter 1915. Even a man with his deep pockets had some limitations.
I think Hugh Wilson probably believed he could do this for Robert Lesley's friend Clarence Geist in his spare time, but when the project was already running two years, with Wilson's other demands on business (he resigned as chairman of the Merion green committee in Dec 1914, citing need to focus on business), etc., I think he gladly backed away from any further involvement, especially since Geist seemed to have hired quality "professional help" in the form of Ross, Reid, and Connellan.
Ross's plans were certainly intriguing and some of the suggestions would have created some bolder holes, but it would be interesting to understand what happened that first year.
Here's what we do know...
By October of 1915, William Connellan resigned.
By 1916, Wilfred Reid had left Seaview and moved to Wilmington CC in Delaware, where he would stay until the early 20s.
And as noted above, some of the most pressing things on Ross's list (like a new, probably safer green for 16) were probably actually done at this time.
However, we also know that probably 80% of what Ross suggested was never done.
By 1916, the world was on fire and it wasn't long before the United States became embroiled in WWI, which brought all frivolous expenditures in the US to a halt.
It's interesting to note that there is very little reported on Geist or Seaview til the middle 20s when a prominent women's tournament took place there. He then became heavily involved with William Flynn building his Boca Raton courses, and it seems Seaview never really was "toughened", or "stiffened" as originally desired.
Today, it seems to be much as it was built for originally; a very pleasant place to play golf requiring intesting and thoughtful shot-placement.
Given that someone probably found the Ross drawings at Seaview, and the fact that just looking at them without much study they do seem to appear much as today's holes, is probably what generated the idea that Seaview was originally a Donald Ross course.
However, I can't imagine that others haven't looked at them over the years seeing notations such as "Present Sand Pit" and not have wondered who built the course originally.