Idiots
First, I have to say: Kenny, you're an idiot. To say that this was a good design decision, while DVI (and VGA) monitors are CURRENTLY being manufactured and sold, is a stupid idea. To claim that it's an attempt to let go of the past, while the displays CURRENTLY being manufactured, just screams of insanity. How can "right now" be considered the past? Only to you and Jobs. Or are you actually implying that nobody would want to connect their notebook to an external monitor?
On to the primary point of my comment... why is it that we're allowing the entertainment industry, who is the only one who wants DRM, to dictate how we use our computers? And why aren't the "green" people jumping on this? If the video card needs to encrypt the stream before sending it across the wire, and the TV/monitor needs to decrypt it, then we're wasting large amounts of energy (compared to sending the signal across the wire as-generated, with no encryption or decryption).
And let's not forget that this is virtually meaningless. Someone WILL break the encryption scheme (if it hasn't been done already). Then they can create a hardware device to go between your precious encrypted content and your non-DRM display. Either that, or (even easier), they'll create a software hack to run on the computer to make it think the display is authorized.
I don't know what's sadder -- the fact that we've outlawed the process of people trying to get legitimately-purchased media to play on their equipment (via the DMCA), or that people have to jump through hoops to get legitimately-purchased media to play on their equipment.