Adam,
I totally agree with you that some of the changes they are having to make should have been figured out beforehand. When I stood on the first tee, the first thing I said to myself was that they needed to lower the hill leading up to the 2nd landing area so the average golfer could handle it. And how they thought a green as small as #2 would help them land a U.S. Open is beyond me. They tried to get too cute with the Dell hole and forced a biaritz on a blind uphill par 5 also. But like I said, I would rather they fix these issues now rather than later. I'm not so sure about moving the green back on #4. I liked it where it was.
Also, Mackenzie and Jones made some weird decisions upon designing Augusta National that have been fixed IMO to make a few of the holes much better. For example, #7 used to be about 315 yards long- just a short, boring, semi-flat hole with the green at the bottom of the hill. They realized they needed to change it when you had guys like Sam Snead routinely drive the green without any problems whatsoever. How they didn't see the current green site benched into the hill confuses me?
Also, we all know that the green for #10 used to be at the bottom of the hill next to the huge fairway bunker. If the tee box for 11 was over the hill (remember the tee was basically behind the current 10th green near 15 tee. So golfers would have had to walk over that hill anyway. Again, the greensite now is much better and more logical to eliminate a fairly long uphill walk to the next tee.
#11 used to be a quirky dogleg right of about 350 yards with just a creek to the left of the green. I don't agree with all of the recent changes to this hole, but you have to admit that making the golfers stand on the top of the hill about 180-200 yards out with that pond lurking makes the hole much more interesting.
Finally, you have #16, which was basically a pitching wedge over Rae's Creek that really nobody liked. Sam Snead had his ball clang off the pin one time and go back into the water... It's a much better hole now and more commiserate with something you would like to see as the 70th hole in a tournament of any sort.
With all of this being said, I would be surprised if the owner of Erin Hills goes with the same designers for the possible 2nd course. As far as I know, this is his first foray into the golf business. I would think that he has learned a few lessons over the past 5 years that he won't want to repeat.
I agree with you on Medinah, but you really think the old #5 hole at Pebble was better than the one they have now? I don't know much about the history of the changes at Pinehurst over the years, but I was mostly thinking about the times that Ross altered his own course over the years. I know Trent Jones redid #7, which I think is a little too much of a dogleg for the average golfer.