Rugby League was born out of Rugby Union. Whilst RL diverged on its own path, it still had elements and rules of Union left over that were redundant to the game of League and should've been changed. A number of them are still there today.
Namely....because Union was an unlimited tackle game, therefore errors like knock-ons and tackles across the sideline were ways for the defense to get a share of possessing the ball.
When RL finally brought in the limited tackles rule in the 60s, it should've changed the rules around these errors too, because they are logical only to an unlimited tackle game.
So ideas like no knock-ons at all, or crossing the sideline is ok, are often popular ideas because other people see that redundancy too once it went to a limited tackle game.
Now, whilst I could argue why these things should be changed, however, every code of football is its own thing, and shouldn't copy ideas from other codes per se.
But as RL evolves it needs to emphasize what makes its sport great and tweak areas of the game that are bad/dull.
I don't want to turn RL into another sport, but what specifically is its selling point? What makes it great? There's no more exciting play in any sport than a long-range chain-passing RL Try, with all the crazy offloads and little kicks and ad lib support play involved. I think everyone would agree that where RL ought to improve on is promoting that more, urging teams/coaches to chance their hand more no matter where on the field they are.
Thus, areas of RL that are bad/dull... 1) the fear of mistakes in your own half, and 2) too much one-out hit-ups, often for four of the five tackles.
Drastic rule changes don't necessarily have to be the answer, like no knock-ons. It can be subtle changes that do this.
At the same time too, you want to ensure the balance of attack and defense is not put out of balance.
There are other little things in the game that should also be tidied up.
Specifically, if a player charges down a kick it should not be a restart of the tackle count. A big defensive play should be rewarded, not punished.
RL has already started to tidy these things up when it started to bring in the Zero Tackle from dead ball kicks, and, players able to do a quick restart from a dead ball or penalty, and, a quick handover play the ball that replaces some scrums, etc. The charge down rule is one glaring area that still has to yet to be tidied up.
But that's about it really. RL does not need to be drastically altered.
Just needs an idea on how to encourage teams to throw the ball around more regardless where on the field they are.
There are ideas like "options" to refuse a kick on the 6th to have another tackle or two to run the ball only. Or, removing knock-ons altogether. Or, no knock-ons inside your own 40. Etc.
But there's a really subtle simple idea out there that could solve this puzzle and that importantly doesn't disadvantage the defense, doesn't imbalance the game of defense vs offense.
It would certainly be an improvement 
