From personal experience, my reading habits were pretty much stale before I got myself a smartphone and got into ebooks. Then it soared.
The thing is not about having a book always available to you. It's more about having a library always available to you, right there in your pocket. It's something very powerful and compelling to a generation fed on short-term fun as TV toons and series and games. You may be reading a book but not into the right mood for it at the moment: no problem, just browse another one, now a short tale, then perhaps some poetry or a philosophy treatise.
You can't have that bringing 1 pbook in your bag.