Thank you for the feedback. Changing the default setting is under review by the feature team, and your feedback is very useful as they are evaluating.
An error occurred while saving the commentRatheesh commented
This feature should be ON by default and Admins / Teams owners should have the permission to set it ON or OFF depends on the business requirements. There are some messages that would require to be circulated from Management and such messages should be notified to all Staff's without fail.