Good read, though I disagree that Amity being like a ghost town would have worked. The way I look at it, the town was just getting over the events of the summer of '74. Things were looking up and the island was finally getting back to normal.
Otherwise, what conflict would there be? Another shark terrorizing a town with no tourists? As the most famous tagline ever declared: Just when you thought it was safe to go back in the water...
To me, that was for the moviegoing public and the fictional vacationers considering Amity Island.