Why the damage can't be repaired?
Personally I don't think maintaining cc gear will be that messy, it's not something op and the scammers are less than 5% of the community... and... what's the problem with player levels? We got 2 years to level up, if they did it faster or not, doesn't matter since is almost everyone at the same level. Sure it's unfair, but they're a minority and that wouldn't be as unfair as wiping everyone's level because a very few individuals cheated.
Anyway, I had not thought of this possibility of them using their things to get cc or lvl up faster that you thought, but I think it's still unfair since they're the very minority...
The levels aren't a huge issue because of the Level 30 Up items we're getting as compensation. In fact, the worst issue I forsee about releveling is the EXP Scrolls from the Popo Gift Box become useless at Level 31, so they can't be used in conjunction with the Level 30 Up unless someone makes a post in suggestions about fixing it.