Limiting Nations is not the way to go. We have a mass amount of players who join this game and then just leave. Imagine a player base 10x what it is now. This would surely change how we play and view the game today. In my mind we need new game features that add more interest, conflict, strategy, wealth... but most importantly, Player Retention.
I like the fact that someone like Ivan is challenging a nation like Spain (pretty much all by himself). He shouldn't have his nation taking away from him and forced into 1 of 6,10,21 nations.
My personal view is the number of ports is fine as is right now. So is the mass choice of nations. If a player wants to grow a nation large enough to take a port or 7 then they must work at it.
Now everyone go buy $10 worth of credits and support the development team and ask for more new fun and exciting content.