Lately I have observed that many 90-120 minute movies would have been a really good 22 minute TV show. It is as if they have one good idea, but not the several it takes to fill the time. When you have only one good idea, the trailer is bound to give away the whole plot.
The opposite is TV shows like the Simpsons, which can have three fully developed plot ideas in a single 22 minute show, but really could have had their own episode each.
It’s like “hey I have a really good idea for a scene” and that gets stretched into a whole movie.
Part of that is the nature of the pitch session. Movies and books are basically sold on no more than 3 sentences, often times just one. It’s hard to boil a 2 hour plot down to 3 sentences, one good scene is easy. It’s also why knockoffs get made so much, “Die Hard in the White House” is an easy single sentence that tells a lot and is easy to grasp... and describes two movies this year (one out already one coming) so apparently sells well.