We anticipate that even with this update, third parties will continue

[Canadane]

SO you've basically punished the law/rule abiding players for what criminals have done

This isn't the first time this has happened, the most recent one that comes to mind is the Waymark change, where you can no longer change them while in battle.
Cheaters have always ruined games for legitimate players. If you aren't staunchly 100% anti-mod, add-on, and RMT, then I don't know what to tell you.

I do think SE needs to punish buyers more than sellers though, well punish both. A slap on the wrist, or worse, nothing at all isn't going to stop them from buying again.