Not a Book

Whatever we're reading on the iPad, iPhone/Kindle/Pretender to the Throne etc., it's not a book.
I feel we need a new name for this type of media, after all we've already created a variety of names for other categories of printed matter to distinguish them from books, e.g., A Newspaper, A Magazine, A leaflet,
or A brochure.

So, apart from cultural inertia, why do we still cling to the (increasingly inaccurate) name of ‘Book’ for long-form text content we read on an iPad, or similar device?

As always: Change is the constant.

Related: Terrific article on the future of the book by @craigmod