I have come to believe that disk space is like freeways - they fill to capacity shortly after you get them. This might add to storage needed. I remember buying a 20 meg (for $750 for my Amiga) and thinking it would satisfy my needs for years.
You are right that it is hard to imagine the need for a $150 1 terabyte hard drive but some research into halographic imaging will probably increase the storage needed by some pretty large factors.
Just think about full sensory input vacation pictures of the future!!
As more people start to use iTunes and other online/digital media sources, the HDs will fill up quick. My personal move collection in itunes is just now over 2TB in size, and still growing rapidly, with 6 TV Shows that regularly get recorded in hi-def. a single Hi-Def Blue Ray movie takes about 16G of space, so 100 of those and you've already used another 2TB worth of video. As standards increase, so do the space requirements.
Yeah, I have heard enough of my fellow students brag about the amount of disk space on their brand new notebooks. I have never bought anything but a used notebook computer, so I have to be happy with disk space they gave you a few years ago. Actually more than plenty!
It is hardly a problem today when you can buy a large external hard drive for around $100.00. I remember my first hard drive was 10MB and I was never going to use that much storage space, and I never did. Now I can get a 2 TB 2000 times more storage.