I don’t understand why anyone would ever think that adding a presentation layer on top of web based content would make it something people would want to purchase when they are not willing to purchase the same content directly on the web.
A central issue with the Internet, no matter what device and presentation layer you use to access it, is that there is an unlimited amount of content available. Evan Williams calls it “a web of infinite information” in this chat with Om Malik. What is valuable is filtering and curation. Restricting access to content doesn’t work. Someone else’s content will get filtered and curated instead of yours. Scarcity is not a viable business model on the Internet.