You can argue it being unfinished based on the story that is contained within the entirety of the FFXV universe, i.e. the stuff they want to address with the DLC and free updates. Supporting the FFXV Universe is not supporting an incomplete story. It's a story that you can expand on yourself, and the best option from the point of view of the creator - but if someone doesn't care about the backstory of the characters or the goings-on in Insomnia, they can skip that and just jump right into the action.

It's a weird approach, but one that isn't necessarily bad in its own right. The fact that there was a vision involving splitting this over media doesn't make it incomplete.