So it's hard not to look at superhero films on this topic but it's the easiest to compare to sequels because as you know there's a lot of them. So let's look at a great example, earlier this year Marvel Studios released Captain America: Winter Solider the sequel to 2011's Captain America: The First Avenger. The film released to rave reviews and shows how to make a sequel. The film takes these characters people love from the first film but breaks deeper into their lives. Anthony and Joe Russo created a film in a completely different genre but with the same characters. Now a spy thriller the film feels fresh and explores themes that are exciting but continue the story from the original. All of this plus beautiful cinematography, it's well written and it's well acted. Basically, if you have two more hours of the same characters lets learn something new and explore new ideas in this world.
Someone should never make a sequel because of money, but sorry folks that's just the way the world works. Obvious sequels are created to make more money but I believe Marvel is trying to prove that sequels aren't always a bad thing. And this could be for the good or the bad. I believe every film could have a sequel in some way or another but the question is not whether you can, but if you should. (Well that reminds me of the moral of Jurassic Park. *crossing my fingers for Jurassic World*