The issue is that OC just doesn't offer any real healing or survival options for DPS.

In Eureka, you could turn the elemental stats to defense, use Eurekan potions and also get the fairy buff regen. Plus NMs didn't really have much unavoidable damage.
In Bozja, your defensive options were more limited without the elemental stats, but you could bring a wealth of Lost Actions for healing, potions and essences that boosted your survivability.
OC just doesn't have the same. The special gear only increase your main damage dealing stat and the special stat that increase damage for PJ abilities. Sure, some PJs have healing or defense abilities, but at times you want to level other PJs.
Just something like the Eurekan potions for a regen effect, or even a potion/essence that perhaps traded some damage dealt for a damage taken buff would do wonders for DPS.