"hardly anyone wants to plug an eReader into a PC just to sideload a book. "
OK,..That's just frackn Lazy!
What do you carry stacks of paper around and say, I don't want to go into the bookstore and actually have to go through the motions of picking up and buying a book? So I will wait until it appears on the pages before I read it!
It is already super convenient to have a bunch of books on the go in one unit. I don't think anyone will be reading all day long that that many books that they cant take a few minutes at home or at work to recharge and reload the E-Reader! This is probably more about content control than anything else:P