Protip: you can rewatch cutscenes at the Inn.

Regardless, Ishgard is locked off to outsiders because most of the authorities are xenophobic assholes.

The Gates of Judgment are opened because of the dual causes of adventurers like us helping them to defend the Steps of Faith as well as the fact that the Dravanian assaults are renewed and intensifying. With the defensive wards dispelled by Ysale, they need all the help they can get.