I think most of us think rebuilding greens should be a last resort! Rebuilding a green is an expensive and a major undertaking especially on a historic/classic golf course. And unlike an old bunker or grass hollow which for the most part can be restored to its original look and playing characteristics, once an original green is rebuilt, it is changed forever. That said, almost every old green has been changed/modified/altered just from routine play and maintenance. But still, the process of converting, for example, an old push up green to a USGA spec is dramatic and very different then rebuilding an old bunker. There are a lot of courses either considering, planning, or already have taken this course of action - rebuilding one or more if not all of their original greens. What drives clubs/courses to take this last resort to determine this is the best course of action?
One other thing I will note is that while it is not easy, especially in the middle of a round trying to maintain pace of play, I wonder how many people really study greens/green complexes when they play them especially if they only play or see the course one time? My guess is very few! How many actually putt to multiple locations on each green to see how the ball reacts. I wonder how many study how and where water drains and look for example for catch basins (to me catch basins around greens are a crutch as they generally can be eliminated with careful and thoughtful grading). How many look to see what happens to balls rolling off false fronts on greens or how well approaches are integrated into green surfaces. Most play a green to the hole location of the day and judge it based on that. If you don’t really study much more then just that day’s hole location by actually testing some different green sections etc, can you really make any kind of strong judgements about the greens? Sadly many still do. Green speeds can change from day to day, week to week on many courses as well.