Maybe cut the number of gates to some reasonable number....? ex. ICN has fewer than 100 gates (83 to be exact) while in AM it has 300, JFK also has about 150 gates (110 to be exact, excluding Terminal 5, and even if we do include Terminal 5, it's no more than 135) while in AM it has 300, even ATL has fewer than 250 gates (232 to be exact). Airports like SFO (which has 95 operational gates) have way too many gates. Not to mention airports like MRY, which have like 6 and can handle aircraft no larger than an MD80.
This I think should make terminal building more worth it.