@Darvin: I disagree. There is dualty in all of the debuffs (i.e. Wizard won't really care about poison, while berserkers will), but they are still balanced. Still, I see your point. Most debuffs are bad to most and fine to a few, while resist down is pointless for most, while unfair to a few.
There is no duality with other afflictions, there is a spectrum
that runs from those that are heavily affected to those that are lightly affected, and it's very rare you'll find outright immunity. With resist-down, you either take a massive loss to your combat power, or you suffer nothing. There is no spectrum, there is no mitigation, there is only those who are crippled by the effect, and those that are unaffected by it.