Corruption shouldn't have been tied to gear, it should have been it's own thing as a sort of talent tree you unlock through drops. So you unlock corruption effects the same way you do now, killing content, then choose which corruption effects you want active with the same perks and drawbacks as they have now with your cloak nullifying some effects. That way corruption still works the exact same, but gear is free to use and you don't have the situation of people having to either A. Bank gear until later and being unable to use a piece of gear when it actually drops or B. Having to make gear "weaker" by cleansing it of it's effects.
The only downside I see to that is that once you have a corruption effect, you have it forever which I assume Blizzard didn't want. They wanted you to make the choice between "Gear piece A with a strong corruption effect" or "Gear piece B with +20 ilvl's, but no corruption effect), which personally I think was a bad design decision. Even if once you unlock a corruption effect you have it forever, you'd still have the challenge of trying to upgrade your gear anyway, which has worked for every version of the game since vanilla and is a core concept of an MMORPG.
So yeah, I think corruption is a good mechanic that was implemented badly, but I don't think giving people a 20% boost is the way to go if they don't want to use it.