Basically as I understand it so take this with some salt;
Previously, Tank Stance would lower how much damage you did while in it.
Now, Tank Stance is removed and we just flick a button to Tank or Not. But at the same time, they reduced how much damage we get from STR on attacks.
So at the end of the day, we don't have to worry about stance dancing but our damage is about the same anyway or at least in the ball park as if we kept Tank Stance on. Or at the very least, not as high as it should be when compared to Melee DPS and their Strength to Damage.