SPOILER ALERT: SIGNIFICANT SPOILERS AHEAD
5. The Mystery of the Mask
In the original trilogy, Darth Vader wore a mask for life support reasons. Why does the new bad guy Kylo Ren, who has no such issue, wear a dorky helmet and a mask? (Cynical hypothesis: it helps evoke Darth Vader nostalgia, so he wears it for no particular reason.)
4. The Sulk of the Skywalker
We are told that Luke Sykwalker went off into hiding after Kylo Ren, his protege in Jedi training, went over to the Dark Side. Why did a responsible Jedi master plunge the galaxy into crisis by disappearing instead of dealing with his issues? In the last scene, the great hero is seen staring blankly into the clouds, atop a cliff on a planet on which he appears to be the only inhabitant -- what does he think he's doing there?
(Cynical hypothesis: there was a need to create a chase, which needed an objective of some sort, and this was a good way to bring Luke into the picture without giving screen-unfriendly Mark Hamill too much screen time.)
3. The Redundancy of the Resistance
At the end of Episode VI back in 1983, Princess Leia and team had totally won over the Dark Side, and the Empire was gone, presumably replaced by the Republic. Leia would then be the natural and undisputed leader of the resulting new galactic order. Why then is she in hiding/organizing a "Resistance" instead of running the Republic itself and using all its resources to crush the First Order like a bug?
(Cynical hypothesis: that storyline might be more logical, but has less entertainment value than that of a resource crunched, albeit unnecessary, Resistance winning against a powerful enemy against all odds).
2. The Ultra-talented Scavenger
When we are first introduced to Rey, she lives as a scavenger on a god-forsaken planet (Jakku), and takes incredible risks to retrieve space junk which she then sells at a junk shop to a weird giant who usually gives her a fractional portion of a meal in lieu ("this is worth ... a quarter portion," he declares, and she shrugs in resignation and takes what she is given). Later, we discover that not only can she fly a spacecraft without previous training, but also that she has enough stamina and martial arts skills to take over the junkyard planet, if not the entire galaxy. Even if we believe that the super-talented Rey wanted to stay on Jakku, passively waiting for her family to return (instead of flying off and looking for them systematically), why does she subject herself to near starvation when she could effortlessly do so much better?
(Cynical hypothesis: tragic and humble origins, even if they don't make sense, work better to evoke empathy for a heroic character.)
1. The Holographic Supreme Leader
I thought Darth Vader killed off the Supreme Leader in Episode VI (losing his own life in the process and saving that of his son, Luke). How then did a holographic version of the Supreme Leader (or a lookalike) re-appear? More importantly, how did he manage to become the all-powerful Supreme Leader, as there is no apparent talent or power that he displays in the entire film? Why is he so dumb as to try to replicate an old strategy that already failed (use a bigger version of death star to kill everyone) and even if it were to succeed, would end up destroying most of the galaxy, leaving him with nothing much to rule over?
(Cynical hypothesis: lazy and/or under-paid scriptwriter.)