Well, you've got to remember that the grip frame on these revolvers represents but one step in the evolution of gun grips from the time of the first pistols. Most of the time, what you see on any given vintage is simply a "better" grip shape than a previous firearm. In my opinion, the S&W frame hasn't evolved from 1899 to now because they haven't received any overwhelming evidence from shooters over those years that the frame was no longer doing the job and needed to be "updated." That, coupled with the proliferation of aftermarket grip panels in recent decades, has left the task of making a firearm fit the end user better up to that end user. S&W was actually a part of that aftermarket supply for many years with the sales of target stocks. Now, I'd say there is no longer enough money in it for them to get back in, and instead offering Altamont grips as the "official" S&W aftermarket stocks.
All of this is my opinion and my observations over the last 5 decades, of course.