Maybe they wouldn't lose their impetus, but they might lose their ability to sell the idea of e-books to publishers. The major stores sell DRM-free music now,

Maybe they wouldn't lose their impetus, but they might lose their ability to sell the idea of e-books to publishers. The major stores sell DRM-free music now, but do you think that Apple would have been able to get music publishers on board if the iTMS had no copy protection on day one?