Dreamworks has a habit of deciding upon sequels the second they have a good box office opening and subsequent weekend. Croods was the most successful film Dreamworks has had since Madagascar 3... and considering Turbo's lackluster performance, probably the last one they'll have for a while. Somehow, people didn't take to Rise of the Guardians, even though it was a solid film.
Yeah, it's been discussed in another thread (Worst CGI Kids Film), but yeah, they were planning on doing upwards of like six of them, but the particular point I was making here was that at the time of the original, they were already planning out the second one before they even completed the original.
The third one broke the franchise plain and simple. The second one was arguably better than the first, with a more fleshed out story line. The third one, while it had some nice concepts, pretty much retreaded the whole Poor me Shrek bit and Puss and Donkey are Frenimies bit. And said concepts took a sharp back seat to those. They had the conscientious decision to make the fourth film the last film, and wrote it much, much smarter than it's predecessors. It comes off as a nice ending to the franchise. Same deal with Madagascar. They
thought about a fourth movie, but someone somewhere realized they ended the story right there, and that anything else would be a mindless retread that takes away the last film's happy ending.
If there's one thing that
should cure sequelitis, it's someone stepping up and saying leave them wanting more.