That fact the game promotes, grand theft, prostitutes, lap dances, sex, killing, drugs, stealing, etc is enough for me and my family. "Extensively marketed and widely anticipated, the game broke industry sales records and became the fastest-selling entertainment product in history, earning $800 million in its first day and $1 billion in its first three days" just speaks volumes.
Its the same reason movies like Pulp fiction, The Godfather, Scarface, Wolf of Wall Street, etc. sell. Once again its about knowing what you're kids are consuming. not all video games are bad.