Sorry for skipping the debate and just answering the initial post, but it makes people's emotional investment feel cheap. It can also feel like they're being hooked intentionally for monetary gain and that the providers are selling out their artistic integrity. Not necessarily, but for instance: Microsoft announces Halo 4, Microsoft puts Halo 4 on 360, Halo 4 is first in new trilogy, next entrants will be on Xbox One invariably, Microsoft feels really bright.
Ya see what I mean? The emotional investment for no payoff is something supposedly fairly exclusive to Americans, if they watched a movie for 2.5 hours, they want payoff, and they don't like waiting a year or more for it to come.
Emob78: Cliff-hangers are great when used efficiently and sparingly. Just like sequels and remakes though, they're overused as a gimmick by Hollywood to inject drama and interest into what are often drama-less and uninteresting stories.
They can also be a bad side effect of editing to try and cover up story problems. Some writers and directors just have a hard time flowing through a solid 3 arc storyline, and end up chopping the plot up into dramatic breaks to try and find a better way towards the climax and conclusion.
This post has the right idea.