It might make the game more interesting if certain policies only become available when certain conditions are met. E.g. some of the more technologically advanced policies might not be available if your country is lacking in technological development + as technology advances certain events occur that are related to technology in society. Another example is drone strike policies might not be available to countries with a ceremonial military.
There could also be events that only occur after a certain amount of in-game time has elapsed, which could make the late stages of a game more fun.