Just read an MPR article:
Predictions from 1996: The e-book
It's a softball, jokey article. But near the end they question why e-book sales didn't take off. Of course, I know you're saying 'agency pricing!' and you're probably right.
But twice they mention reading in the tub. There are already waterproof e-readers, but Amazon hasn't bothered with a waterproof Kindle. And Kindle is, for better or worse, what the general (American) public thinks of when they think of e-readers.
I do wonder what would happen if there was, say, a black Friday-timed commercial showing the latest high-end Kindle and then they dunk it in water. And it works!