I believe that somewhere in the commentary, they stopped the UK version in order to prevent the possibility of the series being sucked dry (I have the UK version on DVD). 12 episodes and a special seemed to work, but it was a little short for me.

I don't see how the franchise is getting sucked dry. If anything, it's taken on a life of its own; the first season sucked, but once you give it its own due (ie, second season), it's certainly a great show to watch. I doubt the English could have thought up "Dickin Flicka." True that any comedy show needs an end (Friends should have ended around season 7, if that), but for the Office, hopefully the Writer's Strike didn't single out a premature end.