That's partly why the [spoiler] of The Empire Strikes Back is effective, but that movie also has a different tone right from the start (even before that, with t

That's partly why the [spoiler] of The Empire Strikes Back is effective, but that movie also has a different tone right from the start (even before that, with the title), and doesn't really tell a complete story but sets up the next sequel to provide resolution and the inevitable heroic victory. Silent Running is a dystopian setting, so the ending is unsurprising, and American Graffiti is a of genre that often has bad outcomes for some characters as cautionary tales.