love it baby! well, not all the time- i agree that it can be annoying, epics like lord of the rings and star wars would suck if they had open endings. but, when used correctly, it's cool, and i love to use my imagination.
i mean look at the road,inception,shadow of the colossus: all of them benefit from having an open ending: they certainly won't have sequels, but they work.it's all down to whether an open ending can make a good film, game, ANYTHING,better.
plus, the thing about open endings is that they can make something that's unbelievably depressing less depressing: imagine how depressed you'd feel if the road ended with everyone dead. likewise, think about a film or game which might of been less sad with an open ending

ersona 4, for example, wouldn't be as heartbreaking if they had ended with an open ending:could the MC come back?
no, says the canon ending. do ye see how it could benefit it if it had an open ending?