I've spent a lot of time trying to tell people that all the stuff in Ember is there for a reason; for example, you're going to need a router, you're going to need support for controllers, etc. I still feel strongly that if your app is large and serious you are going to need that stuff.
But.
A lot of people just want to jump in and start building. React's immense popularity has shown the value in creating a view layer framework without all the extra stuff. It's great for onboarding new developers since there is less surface area to familiarize yourself with, and you can add in extra stuff (work your way towards full Ember) as you go.
It also comes with the added benefit of being able to add small components to a page without running the whole thing as an application, which is a use case Ember was not so great at before.
Overall I think it's a great announcement.