Thoughtful post, Lilo.
I agree with PB. I'd just add that, in the novel, the perception that Vito Corleone "lacked ruthlessness" (i.e., "was a parliamentary debater" during the war with Maranzano [sic]) was deliberate on his part to fool his enemies. The guy who ordered rival olive oil merchants killed, who set Luca Brasi to chop off the legs of Capone's gunsels, and who had a $600k racehorse decapitated, with the head placed in Woltz's bed, was not lacking in ruthlessness.