We tend to sentimentalize Vito Corleone because he was a "good" father, was "kind" to others, rejected drug trafficking, etc. Let's remember that his regular businesses were hardly benign. The big money that he made in gambling wasn't through the odds favoring the house but through loan-sharking--a business of broken kneecaps or worse. And every dollar he took from his labor rackets was a dollar stolen from the pocket of some working stiff. He was against drugs not because he was concerned with the welfare of humanity but because he saw drugs as a threat to the network of corrupt cops and politicians he'd erected to protect his other illegal businesses.

It's true that organized crime exists because society wants the things it provides. If people gave up drinking, drugging, gambling, whoring and the general quest for something for nothing, there'd be no organized crime. But exploiting society's weaknesses hardly makes organized crime socially beneficial.