What pleasures does the gangster genre offer its audience? eg: godfather

One of the most famous films of the gangster genre is 'The godfather' made in about 1970/1 and released in 1972, Based on the best-selling novel by Mario Puzo it's a tale of Mafia life in America during the 1940s and '50s. Vito Corleone (Marlon Brando) is the family patriarch balancing a love of his family with an ambitious criminal instinct. At the wedding of the don's daughter, Connie (Talia Shire), youngest son Michael (Al Pacino), …

…factor in gangster films and the killings are not always expected when you think they are, for example Michael pays the singer a visit to ask for a favor, he gives him fake plane tickets to go to Vegas but you assume he had gone there to kill him, the singer goes to the car waiting outside and gets strangled, differing the way the person is killed to, i.e. not always using a gun.