It's no news to anyone that movie sequels tend to pale in comparison to their original films. This can be disappointing enough to fans, but it can be all the more disappointing when a film has at least one good sequel and then a bad one. It gives us a false sense of security, a belief that the creative minds behind a franchise can do no wrong, and that makes it feel almost like a betrayal when a bad sequel finally comes along.
We've seen this happen in series like Terminator, The Dark Knight, Scream, Shrek, and dozens of others, but the odd thing that a lot of those franchises seem to share is that they didn't start to go bad until their third installment. This occurrence is so common that it's even come to be called "Godfather Syndrome" after one of its most infamous casualties. Why is the third time not the charm in so many franchises? The reasons vary, though a few trends do seem to crop up.
Another common cause of Godfather Syndrome is a change in the creative team behind a film series. Filmmakers have changing passions just like any other type of artist, so it's rare for them to remain involved with a franchise to the same extent throughout its entire run. However, if the director, writer, or any other major player hands the reins to someone new in between films, the change in style is usually noticeable. This isn't necessarily a bad thing, but if the key visionaries in a film series are replaced after making the first two films, a lot of their understanding of the series's themes, character arcs, and overall identity is at risk of being lost in Part 3.
For instance, the original X-Men trilogy saw a change in director from Bryan Singer to Brett Ratner for its third film X-Men: The Last Stand, and this led to a huge shift in the presentation. Major characters acted nothing like themselves, subtle undertones were replaced with ludicrous action set pieces, and storylines set up in the previous films were either badly mishandled or dropped altogether. This sequel simply didn't mesh with its predecessors, and when that happens with the third film of a trilogy that follows an ongoing story arc, it can cheapen all three films.
In other cases, the writers run out of ideas within the scope of the series's universe after two movies and they expand the scope too much in the third one. That's why we got a third Pirates of the Caribbean film that barely took place in the Caribbean and had more characters and storylines in it than a George R.R. Martin daydream.
These aren't even the only three causes of Godfather Syndrome. Sometimes if the second movie in a series ends in a cliffhanger, the third movie gets bogged down with having to resolve those plot threads while also telling its own story. Other times the franchise starts to become self-aware after the second film's reception and panders more in the third installment. And then there are instances where a third film isn't inherently bad, but the second film was just so good that no other sequel can measure up to it. All three of these factors seem to afflict Return of the Jedi, and while it often gets hailed as the weakest film in the original Star Wars trilogy, I really don't know any Star Wars fans who hate it.
Bottom line, making any good film is something of a cinematic miracle. It takes a perfect storm of things going right in order for the product to turn out well, and unless that film is Part 1 of a preplanned story arc, every one of those things has to go right all over again for each sequel to turn out the same way. If a franchise is lucky enough to make that happen more than once, it probably can only make it happen twice -- but that doesn't stop Hollywood from trying at least three times. We fans may see Godfather Syndrome as a stab in the back from the film world, but in the words of The Godfather (and also, sadly, the third Pirates of the Caribbean film), "It's nothing personal. It's just business."