Very occasionally, small countries can be great countries, boutique states with reputations for excellence like Switzerland, Singapore and Israel. More often, small countries are merely insignificant countries; petty in their politics and limited in their horizons. Think of Slovenia, Slovakia and soon, perhaps, Scotland.
And sometimes small countries are dangerous countries, because they are militarily aggressive (Serbia), or financially irresponsible (Greece), or inviting targets for outside meddlers (Cyprus, Moldova or the Baltics) or consumed by internal rivalries that overspill national borders (Bosnia) or in the grip of an illiberal leader (Hungary). It's no accident that World War I started where it did: The incomprehensible squabbles of the periphery quickly become the tragedies of the core.
In his 1993 book "Pandaemonium," the late Sen. Daniel Patrick Moynihan observed that nations are almost endlessly divisible into smaller entities. In 1919 Yugoslavia was conjured into a single nation; today, after several bloody wars, it is six. The cause of an independent South Sudan was dear to Western hearts for many years, but now that South Sudan is independent it is at war with itself. Will anyone there be better off should the competing Dinka and Nuer tribes form their own independent states? Don't count on it. Nations are not the irreducible unit of political identity. Within a nation there are regions, provinces, tribes, faiths, factions, clans. And then it's every man for himself. "The central idea of secession is anarchy." That's Lincoln, in his first inaugural address.