In Avoid being defeated by Zendesk
we see how a potentially panicked user couldn’t find a password he recently saved,
even looking in a CSV dump. If a date field were present he would have been able to find the newest passwords.
(I just did a simple csv export from the CLI. Maybe there still is an option to include the date. I don’t know.)
As for the ability to edit a date, I wouldn’t 2nd guess a user. It’s his data. Give him the ability.