It's all about the money.
The last time I checked, for a $7 paperback book, the author gets about $0.55. So let's assume that all costs for an eBook (plus author's cut) amount to $1 for a paperback. That means my technical books (which run about 5-6 times the cost of a paperback) should be about $5-$6 each.
Now, looking at my bookshelf, I figure I have 70 technical books. Times $5.50 is $385.
I probably spent about $2695 (My God! I spent THAT much?!
) for the paper versions.
Now, if the eBook reader is only $700, and assuming that I can get my techinical books in eBook form for $5-$6 each, I would save over $1000 on my technical book costs.
Plus I would have the benefits of having my whole eBook library in one convient, portable form. Plus updates for my technical books would be able to come out very quickly - because there's no longer a need for the physical creation of the book.
And that's just my technical books - if you factor in the manga and other "entertainment" reading that I do, my savings is substantial.
All this comes at a cost, though: The irrelevancy of publishers.