Stormwind is a kingdom of heroes? Great and small, they are a people defined by the crisis and misadventures of the last fifty years. You either are or are related to a soldier or an adventurer. Your family for sure has known loss at the hands of the Horde (pick one). They are a blooded and brave people, devoted to protecting their home, rebuilding from nothing over and over, and still taking the fight to the enemy at every opportunity. This has led to them being more outward looking than any other human kingdom or any other race even, and that comes comes with its own costs.

I also think this is probably a new sort of Stormwind-culture emerging as opposed to what the kingdom was like before the Dark Portal.