That's great as long as you're reading books that can be comfortably read on a phone screen, and of course many can't. Epub files do have some of the enumerated advantages, and even some more--for instance, they can be used with read-aloud systems and provide other accessibility benefits. They kinda suck for books that require complex layout or large tables or other kinds of complex illustration. I mean, it can be done, it's just less than ideal. I mean, I'm involved in ebook production for a university press, so I know how the sausage is made. And I don't like to buy them.