I agree with a lot of your post. I understand King's philosophy of 'the journey is the point of the story' of course, and I can even let him off for a couple of bad endings to great stories he has done, you need to give a good story the ending it deserves.
I came to that conclusion of how the novel was 'sold' to the readers as the dome being the actual problem and intriguing centre of the issue. This is why I was so interested in this particular novel, now if the anarchy and plot weaving around (or under if you will) this dome actually had a central or a strong link to the concept of the novel, then I would be more forgiving and understanding, but I do not like the whole Rennie plot at all and I think it is quite lazy writing in a lot of places.
I do not see that very much at all with King, but I do feel it is so under-par in so many places. I feel for none of the characters because there is very little standing out from any of them at all for me. He has used kids again to advance particular plot points but I honestly care very little for them, nothing is fleshed out enough for me. There was so much room for expansion (and judging by the size of the book you would think expansion was a major part of it all ) with a plot like that but it seems like Steve has completely dodged the whole attraction of the story that the reader wanted to read about!