The DRM is optional. I'm sure the studios required a DRM option before they'd get behind using it as a video cable, as they did with HDMI. Right now HDMI is at its limit with 1080p, so this gives much more headroom for later HD video standards, or multiple streams.
The spec for the hardware may have DRM optional, but commercial operating systems check for DRM on the video before allowing HD to be enabled.
This is currently true with HDMI, but HDMI isn't wireless. The concern is that actually using the wireless protocol with the added DRM will induce higher latency.