Yeah I don't know. To be clear I'm 100% for Rage no longer being a 'set it and forget it' power. I just don't think a defense hit is a good idea. No matter what armor set you're talking about, it would be a massive hit. In regards to some armor sets, it would make the skill borderline unusable at all when doing high-end content.
If rage can't be how it used to be, I'd suggest disabling 'rage stackng' altogether and just converting it more into a standard build-up. It's a boring solution, but a solution nonetheless.
Alternatively, just nerf it hard. Reduce the damage/to-hit, reduce the duration and cooldown so the crash happens more frequently, increase the endurance cost to activate.
You could also change the defense debuff to a recovery/regeneration debuff.
Just please don't implement a solution that leans Super Strength heavily toward being used with specific armor sets, and leaves other sets hanging. Every Primary should be viable with every Secondary.