Well... you are not wrong in your logic, but your assumptions are wrong... well, because human nature is not what you have been told, and other forces are coming into play that will change the entire game.

An analogy would be like, we, the people on the planet, have been playing monopoly, and T.H.E.Y. are very good at monopoly, but now the game has been changed to LIFE.

So, it looks like T.H.E.Y. are trying to break up all the large countries, so that the one-world-govern-cement can easily rule over them. The US has served its purpose, now its too big to be left with all that power.

Unfortunately for T.H.E.M. the bulkinization isn't going to stop. It is basically going to break down into small communities. Now, imagine trying to govern a horde of small autonomous collectives.

Further, these small communities, tribes, families are going to come together from people from around the world. The people will be drawn to their group and will migrate there. Which will throw the plan that T.H.E.Y. have built to have immigrants destabilize everything in the wringer. T.H.E.Y. won't even know what is going on.