I'd agree with you that the feeds into JFK aren't as deep as EWR's: even LGA has been referred jokingly as JFK's domestic terminal. But TWA had a domestic terminal@ JFK and had feeder flights from ORD & STL; as well as United before they got authority to fly non-stop to LHR from ORD.. And JFK's hotel selection is dismal compared to EWR's . JFK, however is the largest in size, handles the most cargo, and has longest runwayin North America=14,572'. Probably one of main reasons favored int'l gateway for bringing in large planes..Another probably has to do w/pride: the gateway to america has to be in New York, not New Jersey. Besides, in about a year or less, the airtrain connecxtion will mean a 45 min trip from mid-town Manhattan to JFK.