There is a lore reason Ishguard is locked off to you, they do not trust strangers and have not allowed anyone into Ishguard in a long time. They are not just going to throw open the gates all of a sudden and let just anyone into their city. You have to do the quests to earn their trust to gain access as well as some key events which I will not spoil.

I am glad they are sticking to the lore and keeping it locked behind completing the ARR quests. Final Fantasy is a heavy story based game which I love. If this is not for you then you will be better off with another game.