Its important to remember that there is nothing wrong with lending someone your digital book, the same as lending your physical book. You don't need the author, vendor, or any third party intermediary to authorize you. If any party attempts to use DRM to infringe your moral rights, it is morally right to break that DRM, law be damned.
If a person writes a book, and a publisher prints and sells a ton of copies of it without giving any of the money to the writer, that doesn't seem to be moral. Even if it is moral, it doesn't incentivize people to try making a living at writing, since they will rarely be able to compete with big publishers. So: if we let authors claim copyright, and force publishers to come to terms with the authors for an acceptable royalty, then in general there will be more authors. If we balance copyrights correctly, our society = will take some damage from skewing "property" to include "intellectual property", but it should be smaller than the total good of having more authors.