You realize this has far more to do with than workplace harassment, right? Have you never heard of employees using a competitors proprietary information? Or arranging fraudulent financial transactions to cover losses? Or discussing how to mislead investors or watchdog agencies? What do you expect this company to do when they are involved in a legal dispute like this, and have to explain to the court why they have company sanctioned, un-auditable computer systems/applications that helped their employees break serious state and national laws?
I suppose my experience in large corporations is limited. But I'm going to hazard a guess that for all but the biggest corps "company sanctioned" is a not an official term, and that most have given little-to-no thought about all the various ways they need to keep track of the way their employees communicate.
Keeping in context with the OP, Slack allowing admin access to all conversations is a cover-your-ass corporate move, not a solid new tool to combat workplace cultural issues. Perhaps once in a blue moon employee surveillance and bad culture might intersect and prove useful. But that should in no way be used to justify corporate surveillance.
As an elected government official, I understand the importance of papertrails and record-keeping. But the mere fact that so many companies USED SLACK WITHOUT THIS FEATURE, means most had no qualms about side channels being un-auditable before. And now this is just sweet sweet honey to corporate overlords.
