Who cares about Tank Hunter?
Not to put too fine a point on it but killing vehicles hasn't been (nor is it now) that hard with or without that Special Rule. If you really want to kill Armour, that hardly makes a huge difference since you have to hit in the first place. If you really want to kill Tanks (if they are that big a problem in your META) a small allied detachment would serve you a hell of a lot better. The new codex is full of gold star garbage, i.e. price reductions which are meaningless and things like that rule which sound good but which do very little in application in the average game.
I'm a pragmatist. I care about what happens in the average game on a regular basis. Probability is a harsh mistress. Orks can only win a game by managing to get into close combat or somehow holding objectives against those that would shoot them off said objectives or push them off. On the whole, Orks just got easier to kill and scare off. That is all that matters. Giving Orks a rule that makes them more likely to hurt Armour "if" they hit is cold comfort. Winning games isn't about what "might" happen. Winning games is about what does happen every single game.