Further, cheaper books sell more yields more revenue is econ for tots version of capitalism. What book publishers are doing is classic price discrimination, and amazon is damaging it. Note that amazons statistics -- such as they are, and they certainly come with no backing data, and are hard to take at face value since they (stunningly!) support amazon's goals -- exclude sales off amazon.
Authors have seen how apple, amazon, walmart, etc behave towards suppliers. Where amazon to become more of a monopoly, they'll turn their price cutting on authors. It's well within authors' interests (and frankly mine, as a reader) to preserve a price structure that supports writing. Finally, assuming that authors somehow are agitating for "fewer books sold, higher prices, and smaller royalty payments" assumes that authors are all somehow stupid. Perhaps you should revisit your assumptions that lead you to assume that's what authors desire.
ps: since we're almost all developers here -- selling, in one form or another, software with nearly 0 marginal cost -- there's not a person here with any ground to stand on to claim that prices should reflect underlying costs.