You've WAY over-thought this. This is marketing 101 - create a false scarcity, or a one-time deal. McDonald's does it, Trader Joe's does it, and so does everyone else in between. Your blog posts are an outcome expected by McDonald's PR flacks, as are the countless multiple media references to the same. That you don't know why, and that you must attempt to explain it, is the marketing genius behind McRibs (and most of what you consider your free will to choose what you will consume, including politics). They get you into the store and, satisfied or not, you will buy SOMETHING. It hardly matters what, because the average sale is what's important, not the profit on pork or beef. If they can increase both the number of sales and the average purchase, they've created a success.
You can know this, and not like it, and still purchase a product that increases their bottom-line.