Hmm, compared to the changing features of iPhones, how important do you think the new features of iPods were to buyers (especially in the first few generations)? Me, I never used the FM radio or video capabilities of my iPod. I could be atypical. Camera, maybe, but by the time that was introduced the iPod already had a long history of not having version numbers.

And color screen is an interface change, not a functional change, so it doesn't really fall into the set of things I was talking about earlier.