Nobody is really saying high capacity iPods are not necessary, and I doubt many "cannot imagine" why somebody would want one. But like many of the high capacity fans, my media library has outsized Apple's largest capacity offering from the time the first 5GB iPod was released. I expect that will continue to be the case particularly with video and higher quality lossless audio filling up space. My iTunes media library is over 700GB...should I really expect that an iPod of such size will be available any time soon?
I'd argue that the "iPod amateurs" are those who refuse to use the power of iTunes smart playlists to develop constantly updating and revolving sets of songs that keep a representative subset of your music on a smaller capacity device. If you have such a humongous library, it already does and will likely always outsize the latest and greatest iPod, so learning to do this is essential. My 10GB "Perfect Mix" on my 32GB iPhone feeds off 7 other smart playlists in my 80GB iTunes library that rotate through my favorite artists, 5-star songs, tracks that haven't been played in over a year, new additions to the library, cover songs, oldies, etc. I've always got a fresh mix and plenty of choice.
iTunes tells me it would take 41 days to play all the music in my library. I am rarely away from home/resyncing for more than 12 hours, and probably listen to about 2 hours worth of music each day while commuting. Yet I can still have 8 days worth of music on my iPhone. I never feel limited by my "CHOICES"...could you really fill a 160GB with your own music and not find something you like? I cannot recall a time when there was something I just needed to hear so badly that wasn't with me. And if that ever did happen, I'll be home in a few hours and I can listen then. Hardly a tragedy of life-altering proportions.
I do understand the desire to have a multi-TB or even virtually infinite capacity iPod. I'd love to have my entire music and video library with me all the time. But that's just not realistic right now, so learn to take advantage the tools that let you compensate for the shortcomings of modern drive capacity. What I actually expect from Apple as the future unfolds is NOT larger and larger capacity iPods, but continued perfection of the presently clunky streaming technology like Simplify Media that would allow an iPod with no capacity to play your entire iTunes library from anywhere.