1) Lol, why should you kill every dragon? Even Miraak had 3 dragons-servants and he killed them only during fighting with the Last Dragonborn. That means they were useful for him...
2) No, I disagree about "Skyrim is only for Nords". Look, as you know, I live in Ukraine. Yes, they say, that we are nazis, but this is simply a lie. There are a lot of Juwes, Armenians (I personally know one), Georgians are our friends... I even saw few black people. And this is not a full list! And no-one complains!
So what's the problem to live in peace with other races, if they don't brake the local law?