A unified state has the following characteristics:

1. Single currency and market
2. Single passport
3. Single military
4. Single fiscal and monetary policy.

For countries in a similar developmental stage, becoming a single country country can allow the country to become a bigger player in geopolitics and world markets.

Their firms can combine more easily to form larger units and have access to expanded internal markets. Having a single military under a single command structure can also avoid the NATO pitfall of different members moving in differing directions, or contributing minimally.

The downside of forming a unified state is the danger of creating an EU. The richer members leech upon the poorer ones.