I'm pretty sure it's because they repurposed the deprecated Multistrike secondary stat from WoD in order to add corruption to items. Outside of crafted items, the secondaries on all other items are pre-determined and can't be changed so when the item is cleansed all it's really probably doing is disabling that specific stat and hiding the associated UI elements.
It's weird since crafted items in WoD had other items that you could use to re-roll their secondaries. Seems like something they could easily fix, but perhaps they just never took the time to port that functionality to non-crafted items.