I don't think vuln stacks should even have been added to the game in the first place. Failing a mechanic should either just nail you with a ridiculous amount of damage (read as: if you DO survive, it's by the skin of your teeth) or outright kill you, depending on the tier of content you're doing. None of this slap on the wrist crap.

Damage down is fine. That does its job. Nobody likes getting their numbers nerfed into the ground.