Crashing a nation into a setting is pretty disruptive, and I can see why many long-term Forgotton Realms fans didn't like it.
But it has the advantage that the nation itself still has a history and culture, and you now have an entirely new group of people into the setting, that had their old ways and for which the established world is the new ways, where as for the pre-existing inhabitants, it's the other way around. That definitely defines a place for them in the setting, including some interesting dynamics based on that they are new arrivals. This creates many hooks, because you aren't just making up everything about the Dragonborn - they're the Dragonborn from an existing nation, they had a way of how they worked. They might be a bit of the odd man out when they leave their nation and explore Toreil - but they aren't the only ones, there are other Dragonborn in a similar situation, and there is still a definable culture with organizations, traditions and so on that you can base your character on, giving you some material to work with.
