I Am Legend scrapped its original ending because test audiences 'felt cheated' by the big twist
Discussion
(winteriscoming.net)
They pandered to the test audience in the hope of making more money, versus ignoring them and making a better movie.
And what the heck was wrong with that test audience, anyway? Personally I love when a movie manages to throw a clever curveball and challenge my expectations.
Says a lot about the world in general that people want to 'pick a side' and then dislike anything that challenges their support for that side.