Choice means choice, not interoperability. Choice means I get to choose a walled garden or an open protocol.
Somehow people recognize that illusion of choice when talking about Facebook, but fail to recognize it here? Weird.
She can text me, but when I or anybody else On an iPhone try to text her it goes to iMessage and she never receives it.
Yes this is "just a bug", but it also seriously promotes lock-in. It's a very strategic bug, and if she hadn't bought a new phone she would probably be back on iMessage.
iMessage is not always a choice, sometimes it's for life whether you wanted it to be or not.