By comparison, what have we learned from the leaks of the diplomatic cables that was worth people getting arrested by dictatorial regimes or getting killed?
Historians will argue that one for decades. However I've seen it claimed and argued by knowledgeable people that learning what the US thought about their local dictatorships was a major contributing factor that made the Arab Spring possible. Contributing to the freeing of over 100 million people from dictatorship is a pretty good counterbalance to the ways in which some dictatorships have been able to abuse the information released.
See http://www.worldaffairsjournal.org/article/wikihistory-did-l... for information on how wikileaks contributed to starting the Arab Spring.