I'm not sure what the biggest factor is in the explosion of distance in a single generation but it's not good for the long term health of the game, IMHO. There are simply too many social, economic, and ecological reasons why golf courses requiring significantly greater hundreds of yards of acreage is not a sustainable reality, not to mention the effect on the existing 20,000 or so existing courses around the world.
Every now and then someone posts here trying to show that the increase in distance has been stalled using the measured distance of PGA events, and that we've now attained maximum terminal velocity. I don't believe it. I think Erin Hills showed that the issue is that most tour courses do not allow for the dispersion factor necessary for these vast drives today's players are capable of, and the normal 30-35 yard fairway widths cause most players to tone down to keep it reasonably in play on a week to week basis.
However, give them 60 or so yards as we saw at Erin Hills, or as we see at Kapalua, and it becomes a launch fest, with balls carrying well over 300 yards and rolling out to astounding drive and roll distances nearing 400 yards.
Little Ricky Fowler reached the 681 yard 18th with a driver-long iron. The hole is not downhill.
Let's compare that against Jack Nicklaus, one of the longest drivers of his generation, from his 1969 book, "The Greatest Game of All".
Here's how far Jack hit each club;
Sand Wedge - up to 80 yards
Pitching Wedge - 80 to 105 yards
9-iron - 105 to 135
8-iron - 130 to 145
7-iron - 140 to 155
6-iron - 155 to 170
5-iron - 170 to 185
4-iron - 185 to 200
3-iron - 195 to 210
2-iron - 205 to 220
1-iron - 215 to 235
3-wood - 235 yards and up
Driver - 250 yards and up
Jack certainly had some in reserve, but I think that Jack would never have envisioned 380 yard 3 woods in his lifetime.