Democracy 3 didn’t really have many countries in relative terms to the amount of countries that exist. To add more countries in Democracy 4 I suggest that once mods are released with extra countries, if these mods are accurate and the mod author agrees they should be integrated into the game.
Additionally I would like to suggest scenarios where you are given a set of goals to achieve at the start of the game (e.g. Reduce crime by implementing and police state while also implementing a capitalist state) as this would add something new to the game it could also make the game more challenging. (especially if a time limit was added)