The Rift is a game "platform" is the same way a TV is. It's a technology that creatures virtual reality. As long as Facebook doesn't turn it into a different device entirely, it's going to stay a VR headset, which means that people will be free to make all the same games they ever were for it.
I literally have no idea what everyone is so mad about. Is it stupid "OMG Facebook is bad because reasons" or is there actual thought going into it.