> people who buy digital copies should be able to take advantage of the fact that ebooks can update the contents of a book over time, and authors should be able to update their books easily (if they choose to do so).

The important caveat that needs to be explicitly mentioned here is that readers should be able to consent and opt-in to these updates. Authors should be able to release updates, but they should not be able to push them, overwriting the purchased version of the book without the reader's consent. The keystone example of the outfall of giving an author/publisher the ability to tamper with a purchased book is of course the infamous Amazon 1984 fiasco [1].

[1] https://io9.gizmodo.com/amazon-secretly-removes-1984-from-th...