Um...look, cliffhangers are one of the oldest and most often used story telling devices known to man. Cliff hangers are used in novels, TV shows, movies, comics, almost any episodic type of story telling uses a cliff hanger so that the person receiving the story wants to know what happens next. Perhaps you should read more, or observe more in general before you jump to the conclusion that cliffhangers are anything but a normal part of telling an ongoing story. Episodes may end, and different story arcs will complete, but the overall story continues to the next arc.

It's not a cynical marketing ply or anything like that, it's simply good use of a story telling technique that ensures people come back for more.