Why do game companies take hit games and then say... Oh the reason this sold so well was because it dealt with Mythology, there for if we make a game based on another old mythology we'll be a million seller too!
Same with GTA, it must be the fact you play a gangster and have nothing to do with the fact that its a veyr well put together game that's fun, lets ignore that and instead make a more violent gangster sim then we'll eat the profits!