I have a different view on why there was a shift in mentality. After the forum hack the hackers were making money selling hacked accounts to newbies and signature farmers. Many of those accounts were legendaries and people with positive trust. This was wrong on many levels and made some members openly fight it, check the addresses and posts to identify hacked accounts, post about it in reputation, tag them and so on.
I believe account sales should be banned and accounts that were sold after 2015 should at the very least be tagged.
Undoubtedly it did have an impact although I would have thought that members would have changed their passwords and email passwords after the hack was made public. I know theymos released a statement not long as the hack and I know that I personally changed my password despite having a much lesser ranked account back then.
I especially thought that people here on a Bitcoin forum would take security a lot more serious than a lot of the members did. Of course the majority of accounts that were hacked were likely inactive but it still serves the point that they should have listened the emails sent out which I think I recall did happen. I think my original opinion still stands point as well as your point in combination these were likely the primary factors in why the mentality shifted.