One is better than two

We have learned that families were branching off to Nivchar and Nidchar.
Through this, and the bracha that Yizchack gave Yaakov , that he will always rule over his brother, nations were indirectly born that end up fighting with eachother.

What I do not understand is why such a thing as a nation has to be in this world?
The Jews had to come, to be the leaders of the world and show everyone  how to be ethical and moral, but is it really healthy to put people against eachother telling one that he is better than the other.
I see this as an ingredience for disaster.
I think that having nations,and telling one is better than the other, just makes them want to show that they are better and end up fighting. Many world wars (yes both the second and first) were also started because of countries who wanted to show the world how great they are and let everyone share that greatness with them by spreading it.

Telling Yaakov that he will rule over Esav might have simply meant that he will be the political leader, but it could have also been forshadowing to all the fighting and sorrow of today. People branch off because they are different and that opitomizes Yaakov and Esav who were like day and night. I think though that some of the fighting could have been prevented, if only Esav and Yaakov worked together, joining their forces and strenghts rather than putting eachother down so that no one gains anything.