It has been also a long requested and waited improvement: being able to granularly grant administration permission on Office 365 services (SharePoint, Lync/Skype for Business, Exchange) without granting global administrator.
Microsoft has announced this major improvement is going to be rolled out as part of the monthly update process. For those with the First Release option enabled, this should be already deployed (or will be very soon)
To know more https://blogs.office.com/2015/06/11/more-control-over-data-access-with-workload-specific-admin-roles/