Hopefully Nexon catches this quick.

Nexon probably knows they can't win.

Rollback: The economy is restored, but all of the exp, money spent, etc will have the commute in an uproar.
No Rollback: Most (but not all) of the items generated would be deleted. Economy damaged, and commute will be in an uproar.

They probably decided not to rollback for the lesser of two evils (in their eyes)

Rollbacks create significantly less of an uproar with appropriate compensation.

For example, in the situation I noted in the Phantom Changing thread, there was duping in JMS, and then there was a rollback followed by compensation. I lost like 7 levels on my Evan over the time that was rollbacked, but the compensation given allowed me to double that, as well as obtain rare items I didn't have and travel to areas I didn't go to because of extra EXP time. I was upset at first that I lost 7 levels, but that quickly changed and overall I was happy.

Proper compensation will ease the uproar caused by lost time.

On the other hand, they will never get rid of everything that was created and changed with these recent bugs, no matter how hard they try, they never do. The end result is breaking the economy, which is already fu'cked up to all hell and back, even more.