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.
I strongly agree with @Roballo's comment. The workaround we've developed is to add additional users to the Groups to give them view ability to the Group calendar - which has resulted in an exponential increase in the amount of emails flying around the office.
36 votesAaron commented