Thanks for the request. Currently there is a way to set this property through powershell for groups, but it only works for users in OWA. We have this in our plans for Outlook desktop as well and will be working on it.
An error occurred while saving the commentKarin Y commented
This is a must have feature for our organization so that we can use Group Calendaring for company wide information dissemination about events at our organization.
We have announced that Group Owners will be able to leverage existing groups to drive membership in Office 365 Groups.