There's a certain rage against the machine here.
Coaches figured out years (decades?) ago that fancy penalty moves and set plays don't win competitions, rock solid defences do. A lot of the things that set teams up to win tournaments are the boring things - eating well, training efficiently, organised defence etc.
It's a consequence of professionalism in sport, the things that make you more likely to win, or less likely to lose, are invested in more.
The characteristics of the game of the past was often dictated by a distinct lack of professionalism. "Tackling" was appaling. The size of players too was often incomparable to now. "Training" and "nutrition" were often a joke.
That genie is out of the bottle now, even amateur lads are at the higher levels hitting the gym 4 plus times a week as well as on field training. Its going nowhere in the top flight.
So what then? Reduce the number of players on the pitch? It would certainly impact the ability to defend an RL pitch. But the same people harking back to a "golden age" would likely complain it wasn't "proper rugby", despite it being the only way to return to an open running style game.