As several people have mentioned this would mess up DoL completely and for that alone it should just be forgotten.

That being the case even if they could make it so that changing the day night cycle could be a cosmetic thing and became a config option due to the fact
that time is currently connected to the servers... well lets just say this line of coding could probably have bugs upon launch, and bugs possibly associated with
(like I don't know mucking up DoL in some way, even if it wasn't intentional) could cause enough fall out with players to unsub (and some folks have refused to come back after certain things... I know a few people who have quit just because of the way blue mage was implemented). This also doesn't factor in the fact of how upset the community
would get as a whole to work on such a function that only a small percent of the population would enjoy (especially if it caused bugs and broke DoL temporarily).