Ex from GoT - GRRM wanted to make a point about how having power be inherited is a bad idea so he creates a mad King who loses a rebellion After the rebellion is over lots of people have claims so there's permanent war Guess the rebellion wasn't such a great idea, eh?
Why was a weak, small country able to bribe the leadership of a richer, larger, infinitely more powerful one? Because they have a more functional form of government that doesn't force those with power to act purely short term (better loot the place now or the other guy will)