Archeage had something similar to this, where you took trade packs through the open world to a destination for reward, the further you went the more reward. They actually had it very well done where you could craft carts and even ships to carry more packs further.

However the content was only GOOD because that game was open world PvP. There was a risk involved in running trade packs, because you could get attacked by other players and they then could steal your goods.

This created a great amount of open world content because it created a service economy in the game as players would hire bodyguards, or groups would form specifically to hunt down traders. There was espionage, skullduggery and betrayal as well.

In FFXIV I think this type of content would be well... Boring. A cake walk through a completely safe environment, because let's be honest, nothing in the overworld is a threat to the player unless the are really bad at the game.