Yeah, yeah . . . so many of us ONLY want to be able to transfer our books to other devices.
Sorry, but that is not the intent of many. Many would buy and then give their book to everyone they know that would take it. Remember, if you buy a paperback or a hardcover it is also locked to one "format" and you also can't read it on your desktop computer. Digital books are far more flexible, even as they are today than paper. But if the writers and publishers don't get paid for their works, why should they continue to produce.
And yes, while you can share a paper book with anyone, it can only practically be done very slowly at the rate each individual reader can digest it. And that book can never be in the hands of more than one reader. Compare that minimal lending threat to the world of digital, and my ability to share with millions of people simultaneously. One purchase, millions of readers potentially. Anyone who doesn't recognize that threat to the creators for whom this is a livelihood is simply being naive.
I love how noble everyone's intentions are when it comes to approaching the lines of piracy.