Obviously we don't do the same in RL because you can't improve on perfection
Other than playing about with interchanges, I think you're probably right.
From where the game is now, what else could be done that would be an improvement? I liked the rule they used in the NRL 9s with the variable try values, but I don't think that would improve the full game. The scoring is about right, 2 markers is fine, 40/20 is the one unique rule league has that I'd love union to try. 10 metres is fine for the pro game, although I could see why it might discourage amateurs of dubious fitness, but I'm not sure changing it would help.
Actually, no, there is one thing- I'd make the refs get the cards out quicker. But that's not a change to the game, just enforcing the rules that are there already really.