Having all network setup in first stage is fine for interactive and semi-automated install. 
For a real autoyast installation this is again a case where you potentially break existing autoyast 
installation where it is not too uncommon to have quite different network setups during installation 
and in the running system.
So far whatever complex network setup they have is activated in second stage during an autoyast
installation. I definitely know customers (e.g. Teradata) using two completely different network setups 
during installation and later when installed system is up and running.