The thing about Final Fantasy is the series always seems to take from real life. We can spend all day talking about the references.
The most recent Christmas event was a metaphor for the Covid epidemic and to have hope for a vaccine. It even has you communicate with friends via letters because circumstances beyond their control have prevented them from being with you for the holidays.
The rising event even referred to the most expensive piece of glass art that was broken by children playing near it. This is a thing that really happened where children playing near a full glass replica of Disneyland and broke it accidentally.
I think things like Nier or Ivalice being in the game are not only fan service, but continue to expand what Final Fantasy can tackle. There are not many universes that can take anything and then repurpose it to make the lore bigger. But Final Fantasy is one of those things that can.