Thanks for your feedback. We are currently thinking about this. Can you please let us know what scenarios your organization uses shared mailboxes for and what options do you use. This will help us.
We are working on providing the ability to change the email address (both primary and secondary) associated with a group.
Roadmap item: https://products.office.com/en-US/business/office-365-roadmap?filters=&freeformsearch=27891&featureid=27891Anonymous commented
PowerShell is the way to go in this case. See documentation here https://docs.microsoft.com/en-us/powershell/module/exchange/users-and-groups/Set-UnifiedGroup?view=exchange-ps
Or just use Set-UnifiedGroup -EmailAddresses