A large part of the cinema-going experience comes down to there being an air of mystery and an element of surprise. The point is to be entertained, and that doesn't happen if a story is predictable, or if too many details about a movie have been revealed beforehand.
Look at the often ridiculous lengths studios go to in order to protect spoilers and secrets. There have even been campaigns essentially begging audiences not to give anything away, such as #ThanosDemandsYourSilence.
That being said, while audiences typically don't want to go into movies knowing too much, there are often certain expectations and preconceptions. Whether it's thanks to rumours, promises made by actors or directors, or the impression given by trailers and marketing, certain checks can be written that movies are expected to cash.
That doesn't always happen however, as films can always let you down in this regard. While unrealistic expectations can play a part in this - as they did for Doctor Strange in the Multiverse of Madness - other times a certain trust is built by promises, reputations, and insinuations before being utterly shattered into a thousand pieces.
10. Superman's Speedy Exit - DCEU
The world of DC movies has been on something of a tough run for some time now. Though there have been recent highlights in the form of Joker and The Batman, these have been diamonds in a lot of rough, stretching back to the very start of the DCEU and continuing on up to Black Adam, Shazam! Fury of the Gods, and The Flash.
There was one recent tiny bright spot that did at least give fans some hope for the DCEU. Henry Cavill had been absent from any DC production since Zack Snyder's Justice League, and in what was the worst kept secret in Hollywood at the time, returned in the Black Adam post-credits scene.
This was huge and sent the fandom into a craze as Superman was back, and was about to go toe-to-toe with Black Adam. In reality, in didn't matter who stood opposite him, this wasn't about The Rock or the supposed power shift in the DCEU. The was about the Man of Steel, and he was back.
Until he wasn't.
Almost as soon as Henry Cavill officially announced his return to the role, James Gunn pulled the rug from under everyone and confirmed that Cavill wouldn't be the Superman moving forward in the DCU. Talk about getting people's hopes up.