When the creative medium presents a moment that is powerful and incredibly interesting to explore only to say "Actually nah."
WonderWoman (2017): Steve Trevor gives an incredibly powerful speech to Diana who at that point in the movie was under the delusion that humans are inherently righteous and they would only be embroiled in WW1 because of Ares. When she kills the man she believed to be Ares but the fighting continues Steve Trevor has to break it to her that humans are flawed and they all share blame for war. Then the movie ruins that powerful moment by having Ares actually show up and say he was influencing humans to fight.
Star Wars - The Last Jedi (2017) : It is revealed by Kylo Ren that Rey's parents were drunkards and not special. This actually lends to a more hopeful message that you don't need be a descendent of a super powerful dynasty to be force sensitive and make a difference...but actually she's descended from Emperor Palpatine and that's why she's so strong.