Ah! thank you--although I do tend to be wary when I'm on the official Pixar website, as I'm trying to avoid any spoilers for the upcoming films and shorts (I already know too much about "Toy Story 4".)
I know that I can't expect the blu-rays to port over absolutely everything from the DVD releases; another example, similar to the one you mentioned, is the full-screen version of "A Bugs Life" and the featurette about the two versions of the film. I can see why that material was deemed unnecessary for the blu-ray, but at the same time, it was a feature which made the original 2-disc DVD verion of ABL one of the most groundbreaking releases of its day.
In the meantime, I'm going to hang on to my Pixar DVD collection as examples of memorable uses of the DVD format. Pixar has poured as much energy and creativity into some of their home video releases as they have into their feature films and shorts. And I was surprised and please to find that some of the little DVD menu bumpers from "Finding Nemo" found their way to the blu-ray release.
But I would still make the case that the "Cars" teaser is as memorable, subversive, and hilarious as anything Pixar has ever created, and absolutely deserves to be preserved in 1080p HD and avilable on blu-ray.