I am a Server Admin but still cannot access everything because of insufficient permissions.
In the default permission configuration some settings are not available to Server Admins. You can add yourself those permissions using the ServerQuery interface. Those permissions are meant to be limited to the server owner.
The permissions system is very flexible, if you dislike the default settings you can anytime adjust the defaults to your liking by modifying the server template groups. The deployed default settings are what we consider useful.
Don't like them? Change them. Please see the permissions documentation for details