What I'm advocating for now is voluntary compliance, for the following
reasons (and nobody has tried to address #3 yet):
It's a proven system of record keeping that verifies information like
names of subjects, stage names, date of birth, name of photographer,
consent (implied by completing affidavit), and the date the photos
were taken.
The legal responsibility for the accuracy and content of 2257 records
remains with the record holder, and personal identifying information
of the subjects of the photos (and the legal responsibility) remain
off-wiki.
It fulfills the licensing requirements of Creative Commons, saying
that our images must be made available for commercial use, however
currently our pornographic images CAN NOT be reused legally in the US
for commercial purposes because they lack USC 2257. This falls way
short of our "free content" ideals (as well as Commons:Licensing).
All primary producers (photographers) and secondary producers
(uploaders) of pornographic images in the US must keep records, even
if the images were uploaded to Commons by using a pseudo-anonymous
username. For this reason, sexual content transferred from Flickr
without 2257 information should not be accepted.