It is no longer required as part of the HANA Studio. However it still has standalone use cases. For instance it contains the JDBC and ODBC drivers for HANA. If you are doing .NET development you need to install the HANA Client to get the ODBC drivers for connectivity to HANA.
>About the usage: I thought the System View is the View most of the time used. Cause in the course and in the intro every new creation and adaption is done via the System View. Therefore.
I'm not sure what you are talking about. In the course what creation and adaption are you referring to? Most all development object creation and editing is done via the Project Explorer.