Where else do manufacturers decide on the price of the good and not the retailer?
Everywhere. If a retailer starts selling a product below a certain price, that will have its effect on the reputation of the product. Therefore the manufacturer often contractually requires that the retailer will not sell the product below a certain price.
Ebooks should cost whatever the seller charges for them. The publisher's only influence over that should be the amount the publisher charges for wholesale copies.
Also, what about resale price maintenance? http://en.wikipedia.org/wiki/Resale_price_maintenance I just stumbled upon that page from the MSRP page.
Edit: fixed typo