I am starting to agree with you, at least with series that are supposed to end. books like Alex Cross, Joe pickett, etc don't bother me if they don't finish, each book usually can end on its own. If the book has an ending point, these are the series I am really thinking about not starting until the author finishes. Diana Gabaldon will hurt me alot if she doesn't come to a finishing point in the Outlander series soon.