"Suggesting hack makes a warrior = ranger in combat capacity is ridiculous."
I didn't suggest this, you did, by claiming a master warrior can effectively dispense with a shield and dodge. If that's so, then a master ranger can be just as good, with a defense as high and a parry nearly as high, and with a whole bunch of wilderness skills a warrior doesn't get. It might take longer to get there (which I sort of doubt, especially given how rangers have higher wisdoms from what I've seen), but so what.
At this point, we don't know how many classes get this skill. From what little I've observed, it doesn't have a penalty to its use like disarm and bash do. So a few "hackers", even with only a 10% chance per strike, could quickly reduce a shield.
This makes shields less effective. The most distinguishing feature of a warrior, in my opinion, was high shield use. So it makes warriors less effective.
But who knows, maybe warriors (or their equivalent) will just start carry a few light shields in their inventories now. EDIT: maybe we'll even see non-combatants serving as shield dispensers.