Rey mentions the quicksand to BB-8 earlier.
Writer #1: “Hey, we need to disappear Poe’s TIE fighter after they crash.”
Writer #2: “Have Rey say something about quicksand in an earlier scene. Done.”
Writer #1: “Awesome! Lunchtime.”Same deal with Finn and his saber skills.
Writer #1: “How can Finn possibly fight Ren in a saber battle and not get sliced to pieces?”
Writer #2: “Show him fighting a bit earlier with a Stormtrooper who has a saber-like weapon.”
Writer #1: “What value would sword fighting be to a Stormtrooper?”
Writer #2: “It’s Star Wars, man. Just shut off your brain and enjoy the ride.”
Precisely. These are very well expressed examples of contrived screenwriting. Again, just because they slap together an explanation doesn’t mean the explanation makes sense or is good.