Sorry Joanna but I just don't come to the same conclusion. I agree that tactile learning is important but I don't see a direct like between the tactical properties of a piece of paper and the ability of a human to learn to read. Your cognitive example just shows that the observational tools that you've learned to assess learning are based on how the child interacts with a paper book, it doesn't mean that new tools can't be developed to more accurately access them. Adults associate reading with paper because that's how we learned. Children don't have to.
If tactile learning is important I can see possibilities where as children touch objects in a room the word for that object displays on a screen? Of course it would probably end up being "nose", "mouth", "nose", "mouth", "ear", "underwear"....
I think that ebooks open new opportunities to teach kids to learn beyond the limitations of a static page. I saw this TV commercial that demonstrates an early attempt by one company.
http://www.vtechkids.com/v.reader/