Potentially even more important: a leader (terrible or otherwise) who loses power does not have to fear being murdered by his successor, and can hope to regain

Potentially even more important: a leader (terrible or otherwise) who loses power does not have to fear being murdered by his successor, and can hope to regain power. Thus, they have a much smaller incentive to use desparate (i.e. violent) methods to stay in power. That's why the true test of a country's switch to democracy are not the first democratic elections, but the first democratic change of power.