I don't know about you, but I would NEVER start a series that wasn't completed and had no chance of BEING completed, either because the author died, or abandoned it, or whatever. I guess my brain is wired in such a way that I require a sense of completion. I know this about myself, and when I have an option, I'll always choose a course of action that allows for a conclusion.
Slightly off-topic (though related): This being the case, you're missing out on some of the best stuff out there, as many, if not most, of the really ambitious projects or sets never are finished, whether it be Balzac's
Comédie humaine, Tolkien's tales of Middle-earth, E. R. Eddison's Zimiamvia books (along with
The Worm Ouroboros), or the Durants' History of Civilization (which only made it through the Napoleonic Era before they died, despite their working on it for half a century).
It's your choice, of course, but I'd urge you to explore (and quite possibly enjoy) the numerous unfinished sequences out there. Like life, you'll come in on a story which has been going on for a long time, and you won't see the end, but the journey in-between is well worth the risk....
As for the post by Gaiman... while I find the use of the term in this context to be in somewhat poor taste, I can understand the reasons for it; and if you think that this is anything, try reading Harlan Ellison's "You Don't Know Me, I Don't Know You", originally published as part of
The Magazine of Fantasy and Science Fiction's Harlan Ellison issue (July 1977), and later reprinted in his collection of essays,
Sleepless Nights in the Procrustean Bed (1984); I think Ellison answers the point quite thoroughly there....