Because we want our video games and movies and whatever else to have complete stories without needing to buy five more games or watch more parts, which eventually might even not appear.

Lord of the Rings was the best example. They did not make a second movie back then, only when someone else made a real action movie 25 years or so later people who didn't read the book would know how the story goes on.

https://en.wikipedia.org/wiki/The_Lord_of_the_Rings_%281978_film%29

It is just the fact that they setup for a sequel to provide a quick cash-in. It seems lazy at best, as if the game was rushed out the door and you are not getting the full experience. Halo 2 was brought up in this thread and was right on the money. It almost makes the game pointless to experience if there was no real conclusion to the storyline (although I think almost everyone can say that there are games they just play for the gameplay).

Whaaaat? Samurai Jack didn't get finished? Or did I misunderstand?!

I hate cliff-hangers that take too long to be solved, or worse, that are abandoned completely.
Why you ask?? Because the story is abruptly interrupted at its peak and it will take months\years to be finished! (if ever)
If you don't mind about plot, however, that's obviously irrelevant..

Too slow episode releases = hype at beginning, then after months some plot details are forgotten and overall experience is diminished (+ some anger)

Unexpected open ending= terrible, because you feel tricked and you don't know if there will ever be a good sequel.

Abandoned plot (or very bad ending)= time and money wasted, game\movie\tv "series" ruined.. the worst thing to do!

I complained about the end to mass effect 2. For a game that was suppose to be the greatest thing ever nothing happened in that game until 20 hrs in on that last mission and then suddenly it finishes. What a waste of time.

There is nothing inherently wrong with cliffhangers. Like every cinematic device, there are good uses and bad uses. If the cliffhanger interrupts a current "arc" (like Hobbit 2), then it sucks, but if the cliffhanger ends the current "arc" and begins a new one (like Empire Strikes Back), then not many will really complain. Another thing that I personally hate about cliffhangers, is the promise of a sequel that never comes.

The only time I hate cliffhangers is when the game/movie/series doesn't get a sequel.

I think ending on a cliffhanger is equally poor writing, and a try to get us to buy a possible sequel. In movies, it's not as big of a problem as it is on games: movies usually get that sequel. Video games may not. The gaming industry is a treacherous one: companies come and go, licenses may be sold forward, or the game just didn't sell enough copies. In my mind, the story isn't complete until it gets a proper ending: if the game's story finishes with a note such as "and then the baddie was dead...OR WAS HE? Look over there it's clear he is still alive!!" or "Hey there's that tower we spent 25 hours looking for, let's go thEND CREDITS", screams to me the devs ran out of resources/time. I will never forgive what they did in Condemned 2: fucked up and wrote themselves to a corner in the latter part of the game, ended the game on a cliffhanger, and never released or probably even will release the third chapter. Some might remember I've ranted about this before, and that is right: everyone should know what a travesty they did. And I don't mind repeating myself on this matter.

Bottom line: unless you're absolutely 100% sure you're gonna be able to finish the story properly later, OR (in some cases), if the story can still be considered complete even if there is a minor cliffhanger that's not really that important to the overall story arc - finish your game properly, goddamnit!

Yeah, but I think that's fairly standard for the genre. Maxwell Smart never ended Kaos. Inspector Gadget never finished defeating Dr. Claw and the kids never finished defeating Barney.

When you think about it, the quest in most of those shows is just a MacGuffin to push the character forward through the series.

For games people don't want things to end up like HL2 EP2 where fans are still waiting 6.5 years later for a resolution to it.

Well that can't really end. It's all about the never-ending battle between evil and niceness.

Cliffhanger was good movie.

Yeah that is true in most cases, but Samurai Jack was actually cancelled and Genndy Tatrtakovsky has mentioned many times that he wants to finish the story with a Samurai Jack movie.