It is also worth considering Apple's stake in this. Just because they were launching the iPad didn't mean they had to sell ebooks. There were already plenty of ebook vendors and readers on the iPhone, after all.
One effect of the agency model is to make end users care less about which retailer they buy a book from (because the price is the same). A device manufacturer might be interested in encouraging that. For instance, they also might be interested in selling ebooks that only work on their devices to create additional lock-in for the future. An alternative spin would be that they might not want to be hostage to a powerful ebook vendor in the future (the way platform owners often depend on the developers of their key apps).
In any case, Apple's stake was and is altering and, arguably, restricting competition in markets related to ebooks. That's something else the DoJ should be interested in.
One effect of the agency model is to make end users care less about which retailer they buy a book from (because the price is the same). A device manufacturer might be interested in encouraging that. For instance, they also might be interested in selling ebooks that only work on their devices to create additional lock-in for the future. An alternative spin would be that they might not want to be hostage to a powerful ebook vendor in the future (the way platform owners often depend on the developers of their key apps).
In any case, Apple's stake was and is altering and, arguably, restricting competition in markets related to ebooks. That's something else the DoJ should be interested in.