The tripping rule is good for offense, so i'm happy. As for should it exist, I'm in two minds. On the one hand If you dive at and slide into a player then that should be tripping probably. I'm not sure if it makes a difference that you tapped the puck before hitting them. Realistically you have relieved them of possession, but not established possession yourself. Thus all that has happened is you relieved the player of possession then tripped him/interfered with him going after the lose puck