Quote ="Cokey"So if you kick and it's landing say 1 to 3 feet short of the line, you are punished if the defender catches it with one foot in the in-goal area. It would be easier to just run ball on the last tackle and give a set of six if you fail to score,and that would probably be inside the 10m area,so it's pointless kicking in the first place when you also risk giving a penalty for tackling or touching in the air. Yes a try can be scored also,but you should also consider the risk as well.'"
A kick that falls short of the try line is a well placed kick and as a result the attacking side will have the advantage. Where the ball lands determines who gets the greater benefit and is a reward/punishment for good/poor skill.
The penalties have nothing to do with this ruling. You could get rid of the seven tackle rule and idiot defenders would still shepherd players off the ball.