one the great things of internet is the choice you have to buy where ever you want. It's like al those hackers of an iphone. why they hack? they don't wanna be stuck with a single supplier for there apps. you wanna buy what you want and where you want.
therefore I don't care if amazon doesn't sell epub. there are enough other who do. don't make such a big deal out of it. buy somewhere else. if they want that turnover, the will start selling it as well.