I think they just went "Well, we're not getting another paycheck! Screw it!"
The whole season was boring and the ending sucked. He didn't even "talk to his dad" once which was pivotal throughout pretty much the entire series. That's how he was kept in check most of the time.
It was pretty clear to me that in the previous episode when Harry said something like "Well Dexter, I guess you don't need me anymore" that it would be the last time he'd appear.
Anyway, based on a couple of interview articles with the writers/producers/etc.it seems like they wanted us to think that Dexter removed himself far away from everyone he knows and loves, punishing himself by stopped killing and living a somewhat normal, albeit remote and alone, life.
What I got from the last scene is that he reverts to his true nature and continues killing whenever he can. No more worrying about Dark Passenger or The Code, now he just kills.
So he has basically put himself into his own prison.
I stopped watching after season 2. Watched the finale and realized I didn't miss anything.
That's not to mention that it was a bogus representation of a hurricane. For one there would have been massive chop in the water and a lot of wind even before the core of the hurricane even got close. Also, there typically isn't any thunder and lightning during a hurricane. As a long-time Florida resident I've been through enough of them to know.I just watched the finale and didn't think it was AS shitty as some of the reviews (like AVClub's F rating). It was certainly not great, but in the context of this awful season I expected worse. One thing - how in the hell could Dexter have survived driving his boat into a hurricane that in fact destroyed the boat? It's not as though he had a confederate to let him destroy his boat and fake his death by driving him back to shore.
I take the final scene to mean that he is, at least for the time being, done with killing, and that he doesn't intend to reunite with Harrison and Hannah, but I guess it can be taken in a number of ways.
That was almost up there with Seinfeld as far as crappy endings for good series go.
Dexter was a bearded Lumberjack the WHOLE TIME!
The whole show was basically a good dream that went bad.
He fantasized about being a vengeful killer of serial killers and created this whole elaborate fanciful life for himself, to avoid the doldrums of his own true reality.
At the end though, his fantasies started to become more and more nonsensical and contrived (hence the show slowly descending into mediocrity and finally a parody of itself) so he killed off his imaginary self because he couldn't rationalize continuing to create any more mental rubbish and went back to chopping logs.
Which if you think about it, at that point, was a lot more entertaining than his fantasies.
At least he could have shown up in Argentina with Hannah and surprised her. Now, he's decided to have a nut case serial killer of a different flavor to raise his kid.