I understand the rationale, looking at the Golden Age courses and asking whether they have gotten worse is confusing.
Changes have left many worse, but are Pine Valley, Pebble, Shinnecock, Oakmont, National, Seminole, Valley Club really all worse? I know I am being selective, but good restorations can leave a course as great as ever. I have a hard time imagining NGLA being better than it is now, but maybe it was.
If you look on a ten-year scale, I think most of the above would benefit.
Looking at Modern is a little more interesting, because at least we have people who can examine them from opening to closing.
Whistling Straits will get better, both through turf, lack of possible tree encroachment and the wind's effect on the sand and dunes. The original course with its netting to hold sand in place looked a little artificial. The seasons will benefit the bunkering, creating a more natural look (if you can call WS natural).
Harbour Town is better than it was 10 years ago, post reno sure, but grasses withstand play and the trees were there, so that cannot be used. I did not play the course in 1969 - for obvious reasons - so I do not have a level of comparison.
Generally, I find courses on the day they open never to be as great as they could be three years later, though I understand you are looking on the larger scale.
Lastly, if you want to give an owner advice, do not build homes, see PGA West.