They leak it anyway because the general public doesnt follow this stuff and the Apple fans are going to buy it regardless.
No... as someone who has read every article posted on MacRumors and MacBytes* since 2004 (I didn't join the forums until a few years after,) I'm pretty certain I'm an Apple fan and to date I've only bought an iMac, a Magic Trackpad, an iPod, a MacBook Air, two iPhones, and some downloadable content... I definitely don't just buy whatever Apple releases, and I definitely don't buy every generation of the products I do buy...
Personally, I'm holding out for the iBookstore's textbook selection being fleshed out to cover at least a few of my university classes... plenty of the books are available for Kindle, but the eTextbook prices on Amazon are crazy. As soon as they're available on the iBookstore, I'll begin looking into the different iPad models to see which one will make the best eTextbook reader.
*I just realized that this wasn't simply shut down, but that the Mac Blog is considered its replacement. Really? I enjoyed MacBytes a good deal, it was full of interesting articles that often went quite in depth - the Mac Blog doesn't often have articles posted to it and they're never terribly detailed.
MacBytes >> Mac Blog