Why hasn't New Zealand joined AFC yet?

Next year the Women's World Cup is going be hosted in Australia and New Zealand. This is the first time I believe that a FIFA tournament would be hosted between two nations in different confederations since Australia plays in AFC and New Zealand plays in OFC. That just got me thinking why not have New Zealand just try to join AFC. I know the new WC format would give OFC an chance to qualify but in the end its all about experience and the the type of teams you'll play. NZ would definitely get...

Why hasn't New Zealand joined AFC yet?