I was just giving an example of why a rollback isn't as simple as it seems. No need to get concerned about re-downloading the game or anything. Our goal is to get things up as fast as possible with minimal impact to all of you (beyond the downtime).
Well, that doesn't sound good. Wouldn't there be a way around it? Such as, delete all executable files, download the launcher it put in its original place? That way all the data files would be left untouched, and even if one has been modified and deviates from the expected version, only that one data file would have to be replaced.