Defensive Interceptor Wing Question (Golden Rainbow)

What is the advantage of setting up a Defensive Wing, or is it best to just leave them for a defensive airforce?

What I'm asking is, Defensive Land Divisions you can move and occupy enemy land, but I can't seem to find any use for a Defensive Wing.

Defensive interceptor wings automatically respond to enemy air attacks on your own country, or federated countries within its range. So if an enemy attacks your city with bombers, the defense wing will fly to the city and fight the bombers. Hope that helps.