Minority Report
Now that's a horrible movie to begin with, but the cheesy ending literally made my cry out in pain:
- first the villain is faced with a dilemma: should he kill the hero but go to prison for it, or spare him and thus prove that his invention doesn't work. He chooses the third option: killing himself. Why, you ask? Nobody knows, it doesn't make the least bit of sense.
- then, of course, the flawed system is abolished and those wronged by it live happily and quietly in a beautiful cottage
- worst of all, the protagonist doesn't only reunite with his ex-wife, she's also pregnant to replace that dead kid of theirs - ARGH
And don't come at me with that lame excuse "that's all his nice fantasy, they do that in their prison" - there's not one hint that implies that except from how bad the ending is. It's not even seen from his perspective, we see the girl rescuing him and so on, things he wouldn't see in his fantasy.
On a side note: A lot of people seem to complain about endings being bad just because the end with the hero dead or the situation worsened or whatnot. I'd choose such interesting, surprising, innovative endings over the cheesy old standard villain-dead-hero-happy-ending all the time. Nothing worse than an ending predictable to the bone.
Although I have to admit in that aspect, Minority Report's ending wasn't that bad: even I didn't expect the ending to be THAT awful.