To twistedsymphony, I think most of my/your confusion is that this post is about the optical drive choice, not the HDD (sorry, probably me using the wrong termanology for it).
None of these are my ideas, they're from Scobler (who if people don't know works for MS and is part of the channel 9 team that goes around interviewing people inside MS), I'm just repeating them here because I thought that people might find them interesting.
As I just said, they guy works for MS and talks to the Xbox dev team so either he's got the wrong end of the stick or he knows something we don't. He should also have a video appearing on channel 9 at some point in the near-ish future with interviews with the dev team (it's usually less PR based, just him and his camera, and the techies usually give tech details).