All of the different little hamlets serve some sort of purpose, mostly just for job quest lines at the moment, in particular Disciple of Hand ones (like Leeloo mentioned, Weavers in Golden Bazaar).
And like Ace mentions, there'll be other reasons to make it to the hamlets as well when the Starlight Festival begins, too.
Still, can't help but wonder if there is more to them than has been programmed or developed so far. Consider that all the hamlets have at least one or two buildings with guild signs, for example (though the buildings in every place are not accessible or able to be entered in to).
____________________________Final Fantasy XI Character(s) Name:
Carbuncle (RIP Gilgamesh) Jobs:
99DRG, 99PLD, 99RDM, 99WHM | Everything else: 50-60 ~Retired.~ Final Fantasy XIV Character(s) Name:
Satisiun Desain Server(s):
Sargantas (primary) DoW/DoM/DoH/DoL: