No offense axod, but you have a big anti-tablet bias, and I think it undermines your objectivity, the point that you keep repeating your anecdotal evaluation of your immediate family members not being likely adopters as if they were the median. You seem to be reasoning from an n of 3 or 4 people.
I find it easy to see why Apple expects it to be popular. I may be wrong, but the (apparent) fact that lots of people are interested in buying an iPad suggests they can think of ways to use it, and seriously doubt that Apple would be investing lots of money in launching one without assuring themselves of likely demand first.
Me, I would rather not buy an iPad - even though it looks like a very good product, technically - because I am increasingly put off by Apple's aggressive vertical integration and business tactics (like this patent lawsuit). But however I feel about that, I can't deny their expertise in engineering and marketing. Even if I buy a competitor's product, the price and specifications will have been influenced by Apple's offering.
I feel like we (computer users) have already gone through this 'utility' barrier many times - did average consumers 'need' the mouse, the GUI, videogame consoles, color graphics, dedicated monitors (vs a TV adapter) etc.. etc.? Well, no, not as such, but it seems that people's desire for a technology often forms prior to the availability of tools that properly exploit it, even though their use cases may be inchoate.
I'll give you two examples of non-computer geeks who nevertheless have use cases for a tablet, with the understanding that these too are anecdotal.
One is down the street from me: the people who work at the 7-11 use an oldish Panasonic tablet computer for inventory management. they probably don't need multitouch and the software looks a bit primitive, but they seem well comfortable treating it as a digital clipboard that they can hold with one hand and operate with the other. Now, you don't need a degree to work at 7-11 or even to get your own store, just a willingness to work at a small 24-hour retail outlet. 7-11 is a mature franchise business so I don't imagine that they rolled out the use of tablets to their employees on a whim - more likely, such devices hit a sweet spot between usability and capability which proved beneficial for limiting the cost of inventory control.
Another area is for creatives in a studio. I work with audio and video for a living, and for some tasks using a mouse is royal pain in the ass. There is a thriving industry in hardware control surfaces for musicians, and many of them are repurposed by 3d animators, compositors, and other video professionals because the cost of dedicated hardware for the latter is stratospheric. A general purpose device with multitouch is already a winner in this market. Cheaper ones will sell like hotcakes.
Add enough of these market segments together, and you're looking at some real money.