Does that mean once you can be there is no ethical responsibility not to?

Not sure where you're going with that question.

Fundamentally the current accommodation of copyright has two main justifications: 1) Protect economic activity 2) Moral right to identify original author of a work

The point of ease of replication speaks to (1) fundamentally breaking. A human can only produce so much output compared to an AI system.

(2) is a much thornier subject, and not one I really feel qualified to speak on.