Maybe it's indeed a conspiracy. Like that the Cids are the true evil that they are the ones that rule the world. And that they just make up a story so that their dictator-ship can go on. Cid in VII even wanted to conquer space. .

Ok, but seriously now. I think Cid is just a trademark of Final Fantasy, just like Bahamut and maybe also Biggs&Wedge. It's just something that returns that is reconigzed by the fans. Nothing big behind it.