What is the logic in not allowing existing customers to access the discount?

I enjoy Extra and would like to continue it into the new year but these sales keep being for new customers or upgrading. Are they doing some sort of experiment with the price increase to see who is willing to put up with it? At this point I'm just going to let my membership lapse until they have another sale on it. This is ridiculous and an insult to those of us who have been members for years.