I think you're confusing coach strategies and specific player skills, with changes in the game. Personally, and I've watched the game since 1966, the only significant change to the way the game is played occurred in 1967 with the introduction of the limited tackle rule. That impacted significantly on how the game was played. There have been other smaller features such as reducing field goals for 3 to one point in 1971, the ending of the scrum contest in the 1980s, the ending of the contest in the play the ball in the 1970s and the introduction of the 10 metre rule in 1993. However in my opinion the fundamentals of the game have not changed much since the early 70s and the role of the players has also not changed much. Individual players and coaches introduce new skills or strategies, but the game is much the same. The only other significant difference is the professionalism, the intensity of training and the body building, speed training etc. But a winger is still a winger doing a wingers job, same as other positions on the field have their role.
Now you say things have changed since Menzies. I disagree. Menzies was a bit of a freak but not the only one of his style. In the late 1960s to 1970s there was a player who used almost exactly the same tactic. Bob McCarthy. Like Menzies he ranged out nearer the centres and was a terror. Menzies incredible try scoring skills saw him score 0.515 tries per game. McCarthy crossed the line at a rate on 0.484 per game. If he had played as many games as Menzies he would have been up there among the highest ever try scorers. Yet he played forty years before Menzies. Was there much difference in style Compare Phil Lowe with Sonny Bill Williams again 40 -50 years apart. Played similar games. Lowe scored at 0.347 tries per game. Sonny Bill 0.341 tries per game. By the way Sonny Bill played wide, like Menzies as second row and lock. Lowe generally second row also played some lock and played wide. It all depends on the players you have and the strategies you use. But I suggest again, the game fundamentally has no changed much since the 1970s