You want Rage to be a thing where you have to pay attention, that doesn't punish people for having too much recharge?
Make it a toggle--a toggle like hybrid, has no effect on its own, but gives SS's attacks a high chance or perhaps guaranteed proc for something like +20 dam and +5 to-hit that's a 30s duration and stacks up to 8x. But also, while the toggle itself is fairly expensive, have it make attacks more expensive as well. Give people incentive to keep attacking and not let up, but if they ever run out of end and the toggle shuts off--full crash. Dam debuff, def debuff, res debuff, the works--punish them for not paying attention to end and focusing too much on rage.
This way you can still get the benefits of rage--even stacking it--where it actually punishes you for not paying attention to things you need to, rather than whether or not a buff has expired.