To HDD or not to HDD... (Part 2)

So we had a bit of a back and forth about how necessary a hard drive was for a full gaming experience. I was told that a hard drive would do nothing for gameplay, so therefore is not required. I'm going to fire back with the fact that Joystiq and Kotaku are showing off cover art for the upcoming Call of Duty 4 featuring a little badge that indicates a storage medium of some sort, be it hard drive or memory card, is required. For what, we're not sure yet, but it does make you wonder why it would be "required". Could it just be "required" to save progress as has been the case since the start? Or will having a hard drive actually enhance the gameplay in some way? Hopefully we'll see more soon. On a related note, ever since Need for Speed Most Wanted (Xbox 360 launch title), there has been a note saying that the game was enhanced with the presence of a HDD. I haven't bothered checking to see what things are like without one, but it's an interesting disclaimer.