I agree with you it's a big deal, but it's also out of the price range of most of their customers -- until the new design trickles down in a year or two, like it did for the Air. This is the part of the product cycle where you make a product just for wealthy or fanatical people while you figure out how to scale. So their marketing strategy is probably as much about selling the other 5/6 of their product line that people can afford. "Retina Display" is enough to get people's attention -- no reason to also emphasize that the rest of the product line is using an old design that's on the way out.

Just another factor to think about when you decide what and how much to trumpet ...