The potential evolutionary routes of RU and RL is an interesting topic. Whilst RU scrums are more of a confrontation than RL, they are largely uncontested these days. Lineouts used to be contested but the lifting rules has, in the main, stopped that being the case at the top level. So two key ways to restart the game have become a way for the side putting in to get the ball in most instances.
I'm from a RU background but I find these days that professional RL is a better sporting spectacle than professional RU (as there are, in my view, too many super-fit players on a RU pitch and it becomes boring, one-up, squeeze ball). Conversely, at an amateur level RU is better than RL as there's space for skilful running
There's the challenge. Elite (pro-level) RU has little to do with community (amateur) RU. Showbiz rugby, like RWC, is just that, a spectacle for the entertainment of millions of TV viewers and a few tens of thousands lucky enough to get tickets.
Properly refereed community scrums and line-outs are genuine contests but in showbiz? Just a restart (though England's stats suggest not always a 100% guaranteed outcome restart.) for sure. Chicken and egg though, did refs allow crook feed as no one contested anymore or did no one contest because of crook feed?
RL has always been a better spectator sport than RU imo. Even the best games of RU benefit from fast-forwarding through the tedious stoppages.
I'd downgrade a lot of technical peno's, ones that don't endanger player safety, to free kicks, and I'd introduce mandatory YC's for any players committing a penalty offence in a notional red zone, perhaps the 22, and in tandem I'd reduce penalties awarded in the 22 red zone to two points not three. I think the balance needs to shift away from rewarding the non-offending side with 3 points on a plate to penalising, more heavily, and in a way that creates space, the offenders.