Prior to 2016 some people didn't have a problem with it and some had a slight problem but wouldn't go as far as calling them unethical practices. What I think resulted in the shift of mentality was the increasing problem of signature campaign spammers. Account sales were on the rise due to the fact that signature campaigns were becoming very popular during this time which resulted in people buying accounts to cheat the system and enroll multiple accounts.This is unethical obviously because this was against the rules of the majority of signature campaigns.
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.