What asymmetry?

Readers have more information about the quality of a new book in a business model where the book exists publicly and can be browsed in a bookstore, borrowed from friends, etc. than in a business model where the book has no public existence until bought and paid for. This can be diluted somewhat by giving out sample chapters, advance copies for reviewers (but they'd better be trusted reviewers), et cetera, but nonetheless I'd expect it to push willingness to pay down at the margins. Especially taking hyperbolic discounting into account -- readers will generally pay more for a book today than a book to be published at some indefinite point in the future.

The marginal cost of producing new digital copies of a book is miniscule, so it might still end up being favorable to an (established) author relative to dead-tree publishing -- but compared to self-published digital media sold per copy, I'd expect it to come out to a loss. There are other piracy-friendly business models out there, though -- I'm rather fond of Baen's Free Library, for all that their books are unabashed pulp.