Bridgeport is the town that came with the expansion that really introduced music into the game. Yes, there were guitars and the music career before, but Late Night is was really brought it to life. It stands to reason that the townies there are going to be a bit more musically inclined, but I do understand what you're talking about. Almost everyone there has an instrument of some kind in their inventory.
But it would make it kind of hard to jam with another sim if it wasn't like this.