We actually had this in the initial server version but had to remove the feature, as it caused too many issues with network shares. As far as I can tell there's no way the service can connect to a password protected network share (other than running the service under user account, which requires the user to enter password when configuring the service).
This is way too complicated in practice and it always break (i.e. when user account password changes the service password doesn't get updated) so we have removed the feature as it was too difficult to support.
Until we have way to resolve this we won't be running the server as service by default. We might have an option during installation at some point.