Here is a good time to yield the statutory spoiler warning. But don't let that dissuade you from reading the remainder of the article—it may save you a few bucks at the movies.
I admit to holding many gripes with this standard-issue Hollywood blockbuster: basic laws of physics are optional; realism applies except when sound travels through space; an accomplished writer has never written about herself; Lawrence Fishburne appears only to give the protagonists access to the engine rooms, then dies; a spacesuit protects Chris from a fusion (or fission?) reactor's radioactive exhaust; and love magic saves the day (more on this later). But perhaps the worst crime this movie makes is that it insists on a happy ending where none was due.
The issue with this style of ending (ignoring the far-fetched happenings of the plot) is that it forces happiness onto an otherwise bleak tale. No matter what narration they stick on us, Chris and Jen die, on a ship, in the middle of space, without ever seeing or speaking to anyone else again. But instead of allowing us this nihilistic finale, Hollywood forces an idyllic narration that counters the intended darkness. The message—be happy with the situation you're stuck in (so long you have a supermodel for company)—of this forced writing then loses any original value to the depths of shallow platitude. Rather than developing an interesting theme through character choices, narrative structure, visual and audio cues—all of which absorbed without explicit direction—the movie forces us into the theme's sudden appearance without consent, and we are made obtusely aware of not only the theme, but that it has no place in the movie. In fact, I would be hard-pressed to find a theme in the rest of the movie: the characters are too simple to be relatable (Chris Pratt could have died without a tear), and the plot drives the narrative—one event leads to the next event leads to the next. So this Hollywood theme injection not only lacks the film's mood, but also literally injects theme where none exists. Imagine watching Jaws only for it to end with a narration saying, "sharks are the world's most misunderstood creatures, and it is our job as humans to treat them with respect." Passengers is, at heart, a nihilistic film, and to dodge that nihilism in the last few minutes in attempt to make it seem less morose destroys the entire foundation of the film. It's like a magic card trick where, at the end, the magician doesn't even try to guess your card; he just packs his things and walks out the door, leaving you forever wondering what the point of it all was.
Allow me a jump in topic to the other nuisance tucked in this film: Hollywood love magic. We've all seen it, groaned when it occurred, and pretended it didn't happen. Remember Interstellar and how epic and scientifically accurate (to an extent) the movie was until we enter the black hole and Matthew McConaughey's daughter-father love relation saves the day? Or remember the many actors, like Chris in Passengers, who seemed dead before gasping miraculously back into confused life, awoken from a bad reading of their own script? That is love magic, and it's the painful Hollywood gimmick we still endure without protest. What it is, beyond a cliché, is a method to elongate duration and suspense, but mostly duration. You knew Chris survives before he knew he survives. Love magic is only an insult to the audience, telling us viewers that we're stupid enough to feel suspense for the same old trick, played sometimes without added padding (Passengers), sometimes with (Interstellar). It's laziness of narrative writing and our fault for letting it pass so often in blockbuster dramas.
Now I can't propose a solution—that, as critic, is not my job. Make the movie scarier and you get Alien without aliens. Add more living people and you get Titanic (somewhat). But what if, by some strange chance, you don't film half of Jennifer's scenes like the foreplay to a bad porno, and you kill off Chris the way you wanted, and you don't treat the audience like morons, and you allow the movie to be openly nihilistic? Maybe then we get something more meaningful than, "be happy with your life." Because we can always trust the rich and successful when they tell us to be more satisfied with our lives.