I'm surprised by how many people are misinterpreting your argument. I fully agree. The first movie is a great singular story, but the sequel ends with nothing solved and is essentially the first half of a two part movie. Regardless of how good it is (Star Wars 5 is great, Matrix Reloaded is terrible) many modern franchises end their second movie with a lot of loose ends where the main characters seem in a worse position than when they started. The third movie then wraps it all up in a nice little package. I wouldn't say it is always a bad thing, and it certainly isn't true of all franchises. However, for modern franchises, especially big budget ones, that is almost always the case. Franchises like James Bond and Indiana Jones have largely independent stories, and they are apparently a thing of the past. I would like to see more modern franchises start filming movies that can be watched separately but still star the same protagonist. The 1980's action heroes shall rise again!