This is a fascinating document: top 100 passwords from adobe breach
I have a question about one part of it:
However, thanks to Adobe choosing symmetric key encryption over hashing, selecting ECB mode, and using the same key for every password, combined with a large number of known plaintexts and the generosity of users who flat-out gave us their password in their password hint, this is not preventing us from presenting you with this list of the top 100 passwords selected by Adobe users.
So, because in the past we have allowed developers to use symmetric key encryption instead of password hashing, and here they view "using the same key for every password" as a separate problem, what is the big deal with using symmetric key encryption to store passwords? I understand there could be a performance hit because hashing was designed with speed in mind.