There's a couple great books I'd recommend checking out: 'The Power of Myth' by Joseph Campbell, and 'The Storytelling Animal' by Jonathan Gottschall. These books illustrate how stories (and films as vehicles for stories) are vital in how we build civilization and our own psyches. The statement "it's just a movie" usually comes from a place of seeing movies as being mere entertainment. But if you study the history of story, including film, you see that these stories go far beyond than just being entertainment value, especially science fiction, which as a genre is seeking to explore what it means to be human.