It might also be because XII takes place in a huge, living/breathing open world right of the bat whereas XIII just drops you off in one 3/4s through the game and is just big and empty. TH hit the nail on the head that it was real people in everyday situations who needed your help.

Personally I feel like Mark Hunts in both games are cheap filler for side quests and RPGs should have you do more than just hitting things over the head. Monotonous combat aside, XII does fill out its side quest portfolio with exploring for Espers, searching for those hidden dungeons and finding out just how deep the rabbit hole goes ^_^