It's hard to say. One thing to consider is that format shifting is a relatively new idea, especially for books. Doing so without degrading the quality is an especially new idea. So a paperback was always a paperback and a hard cover was always a hard cover, and their value was determined separately. Now we have a new format, the ebook. Format shifting a pbook to an ebook means that we are not determining their value separately.

So here's a few questions: when downloading that ebook for a pbook that you already own, how do you determine which edition to go for? Do you go for the standard edition or the enhanced edition? Does being electronic mean that an ebook has more value? It is more convenient to purchase, will never wear down, and is easier to carry around. Or does an ebook have less value, because you cannot sell/lend/donate it when you're done?

And how do you account for the author's desires? Sure, some will give you a wink and a nudge because they are perfectly okay with the conversion but don't have the rights to make an electronic edition. On the other hand, some authors are very business oriented and view electronic copies as a threat to their control of the supply side economics.

I think the morality of the whole thing is difficult to answer, and different people will come up with different answers based upon their interests in the matter (e.g. consumer vs. author vs. publisher).