Now with regard to the human rights abuses, let me just give a real world example where if the bolded statement made by Adama is true (that a leader is practically good), those types of abuses by a leader are outweighed by the good that is done. South Korea in 1961-1979 was ruled by a strongman/military dictator who engaged in murder, oppression and torture (pretty much everything Cain did...It became a democracy shortly after his rule). But he also modernized SK from an impoverished country to what's become the 13th largest economy in the world and a thriving, developed country. So what do the South Koreans think of his legacy? His rule is regarded so positively that they just elected his daughter the President.
When you're safe, powerful and sated, its easy to have morals. When you don't have these luxuries, someone like Cain is the best option.
What do you think of her?
Hitler has built highways and ramped up industrial production to the point of near full employment in Germany (he needed the highways for military reasons and the industry was built up with huge loans and to lay the foundations for his war engine).
It is honestly a dumb argument.. every dictator aims to appease the largest segment of the population. First through benevolence and gifts and when that comes crumbling down due to huge economic mistakes that benevolence invariably changes to oppression and rule by fear.
As Adama has said militarily she was a good officer.. she had experience, she ran a tight ship, she recognized talent and nurtured it and knew how to conduct a battle. That is not the issue.
The issue is that she willingly sacrificed civilians for her drive to get revenge, she shot capable officers who disagreed with her (bypassing due process present in any civilized military) and she willingly used torture (including rape) against the enemy.
This was the core of early BSG in what it wanted to tell.. if put under extreme pressure will you crack and abandon all civilization and decent human behaviour just to surive and win or will you stand by your principles even if it means death and defeat.
That theme came at a perfect time in our history when the US (and the rest of the western world) struggled with the same question.. how much are you willing to give up for the sake of security and how far will you bend or even break the rules to achieve that goal?
Cain was the antithesis to Adama.. someone who broke under pressure and dismantled her own humanity bit by bit until there was little, if anything left.