The massive reason is actually that pro sports coaches are inherently conservative. There's some interesting studies on NFL coaches that shows that they will consistently take an option that is seen as orthodox (and 'appears' tactically sound) despite the fact that it is shown to be statistically less productive than the alternative.
This. All in favour of the Walker brothers ignoring stats and relying on their sense and the points on the board.
The idea that offloading at will and spreading the ball early in the count tires defences and is more efficient than regulation completed sets makes a lot of sense, and is worth a shot.
I also don't think they need mass roster adjustments. Most pro RL players know how to play off-the-cuff, they're just told not to.