Well, to be honest MXP had always been open since the 70s... It used to cater all long haul flights in and out Milan (i.e.: LIN used to have only european flights. All the flights between Italy and Israel were already landing at MXP. Only the shuttle to Rome used to fly between MXP and FCO).
This issue needs probably to be modeled more accurately in the next games in order to be a bit more realistic.
Just to give you and idea: the Korean Air flight used to fly beteween Seoul and Milan, not Rome. But Alitalia flights to Tokyo used to fly the following route: FCO-MXP-BKK-HKG-TYO.