Good that Nexon have finally been proactive in removing duped items (Now can we deal with these pesky meso sellers in-game?! They're everywhere!)
As for the punishment, good that all people got perm banned. "Knowingly or unknowingly". You see an item that seems 'way too good to be true' then guess what?! DUPED/HACKED/ILLEGITIMATE ! Whatever you want to call it.
You may see it as 'unfair', but you know what? LIFE IS UNFAIR! You just get back up after being punched down, and play by the rules. It's so simple!