One of the questions I have is this - quite a few of the golden age designers called for "fairway cut" around some of their greens but back then "fairway cut" was not green height cut.
No, but "green height cut" wasn't the same then as it is now, either.
There is no doubt that modern maintenance has made it easier to putt from off the green, but it's not like it was never done before 1980. It was certainly done in the UK, as I did it all the time when I lived over there ... but I recall using the putter from off the green at Pinehurst and other places in the 1970's, too.
The key factor is whether the speed of the greens is somewhat comparable to the speed of the fairway/approach. If it's not, then a slight miscalculation on the first part [when the ball is rolling across higher cut] will make so much difference on the second part, that you are better off chipping or pitching. [In New Zealand two weeks ago, it was no problem to putt from well off the green at Tara Iti, but at Cape Kidnappers with more bent in the mix, it didn't work so well even though there is a lot of area around the greens mowed tight.]
Arguably, though, in the old days when the greens were only rolling at 7 on the Stimp, putting from off the green wouldn't have been that much different ... you just really had to whack the ball to get anywhere!