Making the scrum a contest again is impossible at this point.
It would destroy the game.
Imagine if a team kicked the ball out 1m away from their opponents line, they have a decent chance to again take possession after deliberately kicking the ball out.
The contest works in union cause everything is a contest, and possession is not as vital as field position. It creates chances to score in a game where it is very very hard to score tries.
Making scrums a contest provides more opportunities to score, but we have plenty legitimate methods already.
The contest rewards those who make errors and will open up a whole range of dour tactics.
IMO it would change the game a lot too, but not in a negative way. The examples you gave of players kicking for touch would force wingers to drop back earlier in the tackle count, and may lead to the attacking team to throw the ball around more. Having competitive scrums would help reduce the predictability that people dislike in the modern game.