As important stuff like DevForum warnings, promotion messages or strike reminders is all sent through DMs on the forum, letting users disable them is a bad idea. How would the content monitors on here even deal with people that have DMs turned off so they cannot send a warning message, for example?
Leaders (sage+) are able to bypass this setting because they will need to give feedback to users when needed.
An option to turn of DMs will be a great option in my opinion as everybody is entitled to their own privacy.
Feedback can be given on that users thread and announcements etc can go in notifications or can bypass that filter.