I'll finish this up by saying that the producers wrote themselves into a hole years ago when they said they knew how the series would end from the very beginning.
A lot of times, especially when you write for a series with an indefinite end date (as it was in the beginning), you have to break your own story line and come up with filler to extend the life of the show. In that amount of time, you come up with new ideas, create new characters, or extend the lives of ones you weren't going to use (i.e. Ben) because they worked so well. The story, as all good ones do, take on a life of their own. In a way, they tell themselves and the writers just kind of jot it down.
When you come up with this initial idea, a lot of times, it's just a series of images in your head. You think about this really great or clever scene, and you say, "Man, I have to use that." So, instead of actually following the story, you write around those scenes to jam them in there.
The writers were essentially given 36 episodes after the end of season four to wrap this thing up. The problem is that they created so much content in the canon in the first four seasons that they couldn't possibly wrap it all up without changing the entire focus of the show, and they weren't going to break the dual-story formula. Therefore, they had to find a way to make it work, and as a result, they probably left more on the cutting room floor than they wanted to because they had, literally, dozens of characters that needed some form of resolution, and they still had to tell the story of Jacob and the MIB.
I get where the writers thought that this abbreviated season was liberating, but in reality, there was so much momentum and content in the first four seasons that they needed to be the standard 22-24 episode seasons just like the first three. Another 8-12 episodes would have allowed them to spend more time exploring the island's roots, delve deeper into the Jacob/MIB connection, and spend more time developing the flash sideways universe. Heck, even an additional four episodes may have done the trick.
I think that this would have been a very tight, clean finale if the producers went to ABC and said, "This is a 6 season show with X number of episodes. No questions." The fact that they were so methodical and precise in the first four seasons created a major problem in 5 and 6 because there was just too much to clean up in 36 episodes, and it was kind of seen in how rushed the series was at the end.
