The thing about this method however is that there are ongoing server fees etc that they need to try to maintain. Sure they could offer in-game purchases, but monetizing that in a way for them to make money runs the risk of it becoming a Pay to Win game, or something that has sporadic income rather than a solid flow of cash.
8.4 is by no means a bad score. According to what was rated for each part, only the graphics let it down. Personally think they should have waited and kept GTA V for the next gen consoles, but hey, still a solid game none the less :)