I think they may be missing the wider point. Though publishing observers might not think so, the iPad was not principally designed as an e-book reader: if it had been it would have been lighter and with a screen that enable readers to, ahem, read in bright sunlight.
Remember the launch event: Steve Jobs did not even get on to the iBook Store till well over an hour into the show, and even then hardly made a big deal of it.
The iPad's main functions are gaming and watching video, with perhaps reading newspapers a distant third. Over at the Guardian, editor Alan Rusbridger says he spent five hours with his iPad, but doesn't mention books once. Given what else you can do with it, that 85% of users experimented with an iBook is a triumph (in fact since these inititial figures Apple's stats have looked even more positive).
What I think this means is the exact opposite of what some commentators have implied: the iPad will be used to read books from. The publishing industry appears to have taken a giant punt on the iPad, changing its business model in the US for an untested device. The early numbers suggest to me that this bet may work out.