why should the protagonist win?

the clever one wins in a way. it's just that the protagonist is almost always the clever one. he always manages to outsmart the antagonist. :)

I think that might've been the original thinking behind BATMAN (at least these newer, darker ones ... and maybe the Tim Burton ones). And what I remember of Dante's Inferno kinda shows that they all win by losing ("Better to rule in hell than to serve in Heaven")

Don't you watch horror films?

yes, that would be nice too and awful for some..like me. Although it is reality, bad people win over good ones... I think people watch movies to see good endings-happy endings to escape from reality. And, I think the more clever person is always the protagonist since he defeats the bad guy...

I think there are some movies where the antagonist win... I don't remember which one, but I am sure there are... Anyway, I think you're right...Sometimes in the movies an antagonist should win...The problem is that the audience watching movies, want to see good things...They want to have positive emotions, where the "right" is better than the wrong", that in real life is not always so... For that reason, the protagonist wins. It's the desire of the audience that watch movies to find a right world, better than real world...

usually, in dramas this happens a lot. or in the realistic movies, try watching some korean ones.. they're really good and with very intelligent antagonists

I don't agree. I wouldn't like a movie where the antagonist won. I like good vs. evil battles where good triumphs over evil and there's a happy ending. Yes, I like my happy endings. They might be cliche and expected, but I enjoy them! I don't like open-endings and I don't like endings where the bad guys win (And yes, I have seen movies where the bad guys win. They are not non-existent.) If you want to see the antagonist win... then watch horror movies. There are loads of horror movies where the antagonist wins.