The armor system is largely the result of a questionable design of the first game. In a turn based strategic game with very few units, the majority of CCs should be soft to keep the game fun and balanced, but in Divinity: Original Sin, hard CCs are just as common as the soft ones. Of course the designer can constrain them with RNG, but having tons of binary complete disables with RNG would greatly increase the randomness of the game, and many players do not like that.