Hopefully Nexon catches this quick.

I bet the big decision on the rollback decision is all the cubing that occurred over the weekend. As many others have said, EXP can be restored via more 2X, and drops can probably be gained equally though the same 2X, even more if they give extra time.

What I suggest, to prevent the dollar players' uproar (the only important uproar), is to rollback to before even the Australian Miracle Time occurred. Follow that up with whatever suitable amount of 2X Nexon finds acceptable for non-cubers and people affected by EXP loss. The most important part of this solution is a Miracle Time rescheduling for the following weekend, with an even greater chance of rank upgrading, let's say 3X instead of 2X.

This doesn't even have to be implemented, simply stating "We are compensating last week's Miracle Time but increasing, even more, the rate at which item potentials rank up, from 2X to 3X" should be good enough. Of course, actually implementing it in the game would be real nice, rather than just saying it, but there's no way the user would really know, based on the ~50 I read someone needed to get to Legendary.