The best thing about iTunes Match on the AppleTV is it shows that Apple is not afraid to allow the service to stream music without requiring it to also download the music at the same time. While technically it streams to iOS devices just fine, it also downloads the music in the background, preventing you from using it as a stream-only service.
Basically iTunes Match on AppleTV proves they will probably be more open to stream-only in the future, but choose to have it act the way it does for only the present (possibly due to potential heavy traffic).
Stop talking about "streaming". That's an archaic concept compared to the way iTunes Match works. When you use Match on your iOS device, you ARE streaming as you know it, but you're doing more than that. It's a convenience and a feature, not some flaw like you ancient streaming hounds believe.