The original requirement is to stop in north america both directions, this rules out any origination for the RTW except NA (or buy an extra ticket for the 2nd north american trip). OneWorld undoubtedly has researched this restriction and found it to be a clever marketing move. Without this requirement the best price would be to originate the RTW in AKL, buying a GIG-EZE-AKL ticket on QF 116 (but the 2nd NA stop would add too much cost).