Yeah, this ties into the whole problem with recent Star Wars movies and Game of Thrones.
When the writer writes to surprise the audience, not to satisfy the audience, it tends to... well, end up not feeling very satisfying. The problem is that some people who only understand writing on a surface level think "surprising twist" = "good writing", because famously good stories often have really shocking twists or reveals. But in actuality, a good twist is one that the reader could have predicted because all the clues were there, but they didn't. A good twist makes perfect sense in an unexpected way.
Coming up with an original idea isn't hard. Like you can literally just use a random generator like this:
and get stuff like:
Lynne is a giant fuelled by hatred, who stalks teenagers and keeps their fingers in a jar. Detective Brooklin, a virgin from Waukesha, knows she has to stop her. Eventually, Brooklin captures the villian and wins back the respect of her estranged family.
Yep. This story about a virgin detective with an estranged family who captures an angry giantess who... collects teenagers' fingers is definitely original! Good job, computer! Nobody else has ever come up with that!
...But that's exactly the problem. Coming up with a story that's different from anything anyone else has made by just throwing together weird, random combinations is so easy even a computer could do it. Coming up with a story that's unique but also thematically coherent with some kind of logic that makes it all feel like it goes together is the hard bit. Similarly, if somebody guesses your story's twist, it's easy to just change the solution, but not necessarily good, because it usually means that all the clues pointing to the original solution no longer make sense.
"Ha! You thought that one of these characters who would make thematic sense would kill the big bad! Well, I fooled you! It's actually this random character who was hundreds of miles away and got here impossibly fast and whose character arc had nothing to do with any of this! I'm a good writer because you didn't predict it!" YES I AM STILL SALTY ABOUT THE GAME OF THRONES FINALE FFFFFFFFFFFFFFFF-! 
