The point is people have multiple computers nowadays, tablets, notebooks, desktop, tv etc. It's not a tablet *or* a desktop, it's a tablet *and* a desktop. iPads are perfect devices to carry around for reading and light internet access or to play some games. I wouldn't live without one now but in no way does it replace my MacPro or the MacMini attached to the TV...
You plucked the words out of my mouth! The iPad is the perfect *complement* to ones computer setup, instead of having to lug around a Macbook just to be able to have internet/mail and such, you have the iPad which does almost everything one could need when on the move, and for a longer period of time than a laptop/netbook without recharge.
I recently discovered Beneath a steel sky and the Broken sword games for the iPad. Happy times! :-)