I said in my PopMatters review of 80 Days that the titular 80 days of the bet that inspired this trip around the world in the first place is a macguffin. The real core of the game is the act and art of traveling through the foreign locales. The sights, the people, and the adventures are what matters. They matter far more than making the trip in an arbitrary number of days. Whereas Phileas Fogg is content enough with his cabin and his newspaper, we play as Passepartout, and he is out and about finding information about travel routes, making trades and getting into mischief.
That much I still believe about the game. 80 Days is the artful worldbuilding and allowing the player to explore it that matters. Given that the 80 days may seem like an extraneous challenge for those who have already explored the world, it is nonetheless an important component even to those who wish to experience the title as interactive fiction and not a challenge.