When I got my first touchscreen phone about three years ago I realised immediately that touch was going to be important. It is such a totally instinctive and natural way of interacting with a hand held device.
The important bit there is hand held... though I now find myself trying to touch my laptop screen all the time when I'm using it on my lap. When it's on a desk, that urge goes away, because my hands and forearms are settled firmly on the mouse & keyboard.
Anyway, earlier this year I bought an iPad for my techno-phobic mother. That was my first experience of a tablet and I'm afraid I very quickly cracked and bought one for myself. It became a very comfortable way of interacting with the net and basic applications, the "always on" and silent operation is excellent, and I have become totally sold on tablets as (a) a mass market device for the basic computing most "normal" folk need and (b) another niche-filling device for those of us who enjoy technology a little too much.
When the Nexus7 was announced I realised immediately that a smaller, lighter (and cheap!) tablet would be even more useful than my iPad most of the time, and I've been proved right by the last week using it. A device you can stuff in a big pocket, hold comfortably in bed, and take anywhere with barely a second thought is very handy.
Of course for most people a phone fills that niche already. But the larger format is very convenient, especially if your eyesight's not perfect. So there's a crossover zone in which big (or very high res) phones and small tablets will naturally co-exist.
Overall there may be a faddy element to some tablet mania, but as I said above, there is no doubt whatsoever that touch devices are here to stay, and I understand why Microsoft are panicking, hence the compulsory Metro interface without an on/off option for the tablety stuff. They're right about adding a tablet interface, but wrong about that on/off toggle.
I've made this point before but I kind of like it: items likes phones and tablets and PCs are becoming like shoes. One pair can carry you anywhere, but different footwear suits different occasions and uses, and can radically alter your experience. As Steve Jobs said, not everybody needs a truck/desktop PC, and I'd certainly say that nobody needs a tablet, but all these things have a place and a purpose.
</ramble>
