+1. AMD couldn't have pulled off these kind of shenanigans if they hadn't locked down the consoles. If it was just PC that would have started an API cold war. If you're just a PC dev then Mantle won't matter. If you're a multi platform dev, then it has the potential to be the only game in town. After all, even if Nvidia spins their own low-level API it will be PC-only. Why would you want that? When you can have "more and more".
"Open" in this sense means it's not just AMD PCs only. It's also AMD-based Consoles as well.
They would have to port of dx anyway, but if mantle just works because of the console version why not include it as an option?