None of the Final Fantasies prior to 7 had FMVs, and I can name two at the very least that have much better plots than 7. FMVs are a nice bonus, but they're not integral in any fashion. They don't tie the story together at all. All they do is add cinematic quality to the action sequences. You need text and conversation to really further the plot. An FMV of Aeris' death certainly pushes the story along, but it's meaningless without the text to explain how the characters react to her death. FMVs enhance the story, but they're not necessary at all.