Google TV Streamer disappoints, as it doesn't support 4K 120Hz out of the box.

I received my Google Streamer this morning, plugged it in to a brand new HDMI 2.1, ran all the setup, and went straight to the settings to find out that the display resolution maxes out at 4k 60Hz. Why did Google bother including HDMI 2.1 support if they're not going to support 4K at 120Hz?