NeverarGreat is bringing up some great points. I think the very fact that so many people (at least that I have talked to) thought that Rose crashing into Finn made no sense proves this. Because they felt (as well as I) that the movie set them up for Finn making a successful sacrifice.
That’s just how they interpreted the scene, as well as how I did. Doesn’t make it more right than an alternate interpretation, but that is kind of how movies work. They are meant to provoke different opinions from people and readings of the same material.
The Last Jedi in my opinion, for that scene, presented it in a manner that set us up to be angry and puzzled with Rose’s decision. Just my reading of the scene.
I think most disagreements over TLJ originate from people presenting their interpretations of certain scenes as the only valid—and therefore obvious—interpretations, with any interpretations running counter to theirs being completely wrongheaded.
I’m not trying to say every scene has only one proper interpretation, but rather that your preconceptions of how the story should go color how you interpret a scene. Knowing this is Star Wars and the heroes don’t die, Finn’s life is never at risk and there is not chance of him destroying the weapon because he has to live for the next film. That is a Star Wars Trope.
Someone seems to be conveniently forgetting The Phantom Menace.
Who dies in that one? The only main character to die in their own trilogy was Padme. Each trilogy has a trio of characters with some side characters. Obi-wan, Anakin, and Padme in the PT. Luke, Leia, and Han in the OT, Finn, Rey, and Poe in the ST. The Jedi mentor has died in each trilogy (Qui-gon, Obi-wan, Luke). Other characters die (Darth Maul, Mace and most of the Jedi, Jango Fett, most of the fighter pilots in ANH, Boba Fett, Jabba). But many others live. But the main trio will live to the end of the trilogy. And R2 and 3PO are around to the very end. People die when it is important to the story that they die.
Sure we don’t think Finn will die (though I thought we were judging the movie on its own terms, not in terms of the broader Star Wars saga). But is Finn’s plot armor the reason Rose saves him? Besides, you’re conflating the idea of whether he could sacrifice himself to destroy the weapon with whether he will. We know he doesn’t, but this has no bearing on whether or not he could physically have accomplished the task had he not been diverted.
I think we are shown that he cannot damage the weapon enough to stop it. His craft is slowing down, it is crumpling. If the cockpit canopy goes, Finn is dead. If it gets the engine, he is stopped in his tracks. I think we are shown in many many small ways that his sacrifice would be in vain so we are supposed to be glad Rose saved him from dying without purpose. And when Rose’s craft hits Finn’s, we see how flimsy they are. Not enough mass or structure to do any damage. A fully functioning speeder might have been able to do some damage at full speed if the weapon was not active, but with it active, it has slowed down Finn’s speeder, it is crumbling it, pieces are coming off, and Finn has no chance. When I first watched that scene I saw the weapons crumple and I knew it was hopeless and I routed for him to get out of there. So when Rose made him by crashing into him, it made sense. I really don’t know how you could see it any other way. But this is Star Wars, not Game of Thrones. In GoT I would have expected him to die, but in Star Wars I don’t. So both in terms of the movie on its own and as a Star Wars film, I didn’t think Finn had any chance or would die.