I think they chose this model because monthly subscription-based console games have historically awful sales. This model allows them to rake in the cash a successful subscription model brings, without scaring away the hyper-conservative plebs who see anything other than a $59.99 pricetag plus DLC's and throw a tantrum. This hybrid model is great, and allows us dedicated players to have an outlet of enjoyment for over a year (and probably a couple more years) for no more than standard games would cost over the same time. Grow with the times, or be left behind.