It's been joked often on the internet that Smallville should have been re-named "Metropolis" by now, seeing as the town of Smallville barely features in it anymore.
On the other hand, I choose to think of the title these days as a reference to Lois's nickname for Clark (which, by the way, this show cribbed from Superman: The Animated Series
, just as it cribbed Jimmy's "CK" nickname for Clark from Lois and Clark
). So it's not a show about Smallville, Kansas anymore, it's a show about Clark "Smallville" Kent.