OK fair cop - sometimes players do give a way possession; its generally a trade off for territory. I was considering simply the terms of the situation as described - so if I may rephrase - I have certainly never seen a player willingly give away possession to opposition close to his own goal-line.
However my basic point remains - why on earth would we assume that player kicking the ball through a ruck is actually trying to give possession to the opposition rather than create a chance for himslef or team-mates to move onto the ball going forward. i.e. "win" the ball.
To penalise a player who legally part of the ruck for kicking the ball forward seems odd.
Especially given the fact (as you all rightly say) that players kick the ball forward constantly in every game.