I think the change began in the 70's when some of the cue makers began to recognize that is cue is an instrument and not just an implement. I have been playing for more then 50 years and the first cues I owner were almost like clubs. Even many of the well known production cues back then were not well tuned instruments. You don't have to take my word for it a lot of those cues are still around. Cues like Viking, Palmer, Brunswick just to seemed to be built to knock balls around with what seemed like no real thought to, "Can we build a better playing cue"?. Even many of the cues by Balabushka and Martin were club like.
I think the first cue I owned that I felt was a real instrument was a Gina cue I had made in 1971. People would pick it up and say, "This thing is so thin and flimsy feeling". That was till they played with it for a while and found it made you a better player, the cue became an asset. Joss advanced the move for better playing cues probably more then anyone in my opinion. Cues now mattered, the taper, length, butt diameter materials and so on the goal was a better cue for the customer. I haven't heard someone say in a long time, "If you can play you can play with anything, I saw a guy win with a broom handle". That is not true, the cue can be the difference in closely match competition. I personally saw Parica lose a $5000.00 match and the proposition was he had to use a house cue. Parica made the offer and was sorry he did. He had been playing there all night so I think us rail birds had a pretty good handle on his game that night and the switch to the house cue knocked down his game a good 20%.
No doubt it, the best cues and most technically advanced cues ever built are being built today.