People are not really going to willings to just go to an ereader (iPad or kindle) for anything but the plain black text on white paper which is what almost all heavy readers read any how. In that area the kindle wins.
That is one heck of an assumption to make and I completely disagree with it. It doesn't surprise me that a Kindle owner/lover would make this statement because the Kindle can only be used for one type of text. I do all my ereading on the iPad. Comics, magazines, newspapers, children's books, technical books, books with pictures, pdf's, and novels.
I have no idea why you think people wouldn't consider ereaders for these other types of reading (my kids love reading the children books from the iBookstore). Very short sighted of you.