I once asked a saxophonist busker to play the godfather theme tune for me in Sheffield.
He said he'd not heard it.
People enjoy playing these types of games because everyone has fantasies of being a rebellious, powerful, feared, evil badass that can and will kill endless amounts of people at the slightest whim, and the games are a handy, harmless outlet for it.
Just the Mafia? I guess that's ok. I'm reminded of Snow Crash (paraphrasing): "There's a reason no one ever calls The Family 'the Italian Yakuza.'"