Locked down tight, almost nothing to learn, no way to screw it up or wind up pwned by malware.
The real question is, why are so many creative, roll-your-own geeks also possessed by this gadget?
I'd like one for the simple reason that I wouldn't have to be tethered to a computer and keyboard when I surf the web, or Freep. I like to multi-task when I watch TV. Lying on the couch and ipadding at the same time sounds great to me. You can't do that comfortably with a laptop.
You have asked the right question. I met an old-time grizzled C++ programmer who loves his iPad. And then I see 5 year-old kids using apps on it. It appeals to a lot of different people.