Television and movies have a tough time going about the long-foregone literary device of the dénouement. If you recall, the dénouement is that point of the story where the dust settles for the characters and readers—not necessarily where plot lines are tied. It is that point after the crisis (which television and movies have trained us to be The Ending) but before the ending which makes the impending ending appropriate.
Society has a different inner voice; one that sounds more like Nickelodean or Michael Bay and less like Heroditus or Adam Smith. That, in the end, is likely why Battlestar Galactica was canceled and aired its final episode this past Friday with such an ending that it would ensure—amidst the regret of seeing such a show go by those who got it—no DVD’s, no movies and no sequels. (Any subsequent stories should rightly occur before the events that transpired in this episode and not after.)
The reason is not that complex but it will take Battlestar Galactica spoilers which will occur after the jump.