The iPad's target audience (as in 99% of users) DON'T WANT a file system, at least not one they have to see and manage. That's the point. Keep it simple. Apple is great at that.
Really? Do you have any hard facts to back this statement up or are you just stating your own opinion as fact?
Anyways, the fact that apps like Air Sharing, Dropbox, and Good Reader are extremely popular clearly supports that people want an area to keep their files. This is a fact because this is what these apps do, they store your files on your iPad/iPhone/iPod.
Therefore, it's clear that people do want some sort of file system. Likely nothing fancy, but an area where they can store their files and easily access them.