Good morning Ian, I like it also and the ball out part is easily explained.
However:
1. One could argue that is not written law "clear of Bodies"
2. One could argue that the SH hands hands in the ruck and is also offside as his foot is forward of hindmost teammate. I know we allow it.
3. What is so odd about requiring that last foot of the ruck to push the ball out or step over (similar to RL) it as the SH reaches to play it? So it is actually out. I know clarifications exist to allow SH to dig or otherwise we would have scrum after scrum.
The difference with RL is that they can afford this because the defending backline is 10 metres away, and the defending markers (the two opponents marking the player playing the ball and the dummy half) must be "square" that is, lined up directly ahead of the play-the-ball and behind one another parallel to the touchline ("markers not square" is a PK in RL)
In RU, the defending backline is only one or two metres away, depending on how "deep" the ruck is, and in the modern game, rucks are very shallow because teams do not commit more than two or three (often less) defenders to the ruck. Consequently, the defending line is very close to the opponent's HMF.
Were we to apply your suggestion, the acting SH would probably be scragged more often that not when he tried to clear the ball, then what sort of game would we end up with?
What you suggest worked in the past for two reasons
1. Rucks were much, much deeper, with more players committed by both sides, so the defending line was further away, and
2. Players were less fit and considerably slower, so the acting SH had more time to clear.
I mentioned that RL has the defending line 10m back. It used to be only 5m until about 20 years ago. The reason that it was changed is was precisely because they recognised that players were becoming faster, fitter and stronger, and that was resulting in it becoming too easy for defending teams to stifle the attack.