Movies are hideously complex, and directors and editors are tweaking the final product up to the day the last reel is due at the studio (and sometimes a bit after). This process means a lot of stuff ends up on the cutting room floor, even that which should have been in the movie in the first place.
Screen Rant gives us “10 Deleted Scenes That Should Have Made The Final Cut”.
Cutting scenes is not an exact science. Take World War Z. They cut all the blood and gore from the movie (to such an extent that episode three of Fear The Walking Dead is gorier than Brad Pitt’s big budget PG-13 zombie horror / action movie) and all that cutting ruined the film. The original edit (aka “The Unrated Version”), however, was a brilliant movie, one of the best zombie flicks I’ve ever seen.
OTOH, some things SHOULD be cut. Like most of the three Hobbbit films, for example. I just watched There and Back Again, A Hobbit’s Tale recut by David Killstein, which chops the 7 hour, 54 minute running time of the three movies down to 3 hours 10 minutes. Again, it is brilliant. It is fast-paced, focused, and simply not boring. And most of the bad CGI is GONE.
Filmmaking is an art, not a science. And many, perhaps most films are salvaged in the editing room. That’s where the raw footage is massaged into something hopefully watchable, possibly decent, and maybe even great.