Oh, yes! I very much want character development, as well, of course, and backstory. I'm not as convinced as you are that the Others will have enormously logical explanations, but I wouldn't be shocked if they did. I do think that there will be some lovely themes of leadership and ruling in the last book, as well as some wonderful development for all major characters. But I also believe that the Valyrian steel swords are like your Checkov guns, right? They've been too crucial to the story to not be crucial to the end. Of course, the show won't do everything that the books will, and so it might gloss over everything but Lightbringer, I guess.
I really think we'll get Lightbringer, and possibly this season! Beric is headed to the wall. Beric's blood magically lights his sword now that he's risen from the dead. Jon has risen from the dead....