Creating new entries in venerated, mature franchises requires a balancing act that is far from simple. On the one hand you must make sure to retain those core pillars of design that are responsible for your games' success in the first place.
On the other, you can't ignore more modern gaming conventions and components - doing that will turn off any potential newcomers to your slice of the gaming rainbow.
This is a problem that Final Fantasy must overcome with almost every release, the Japanese role-playing game consumed by the blessing and curse that is long-term success. Making Final Fantasy XV feel both fresh and 'Final Fantasy-esque' is a constant challenge.