A New Traffic Sign: "Take Turns"

The inventor Gary Lauder unveiled this new idea at the TED conference: A traffic sign that instructs drivers to "take turns" at an intersection. The TED blog explains:

Half a stop and half a yield, the sign gives each driver a clear indication of how to behave. Below the red "Take Turns" shield is a small sign reading, "If Cars Are Waiting, Please Stop and Alternate." And if there are no cars waiting, just blow on through. (No more stopping at red lights at 4am, on a country road, when there's no one around for miles.)

The ice cream cone shape isn't quite as simple as an octagon. And if you were unfamiliar with this sign you might wonder how to "TAKE TURNS." A sign that just says "STOP" is pretty unambiguous.

But that said, I think once people got the hang of the "TAKE TURNS" sign, it'd work well. If you see someone waiting at the intersection you're approaching, you stop and let them go first. The only problem case that I can think of would be two people approaching the intersection at the same time from perpendicular streets and both trying to "blow on through."

And as a general point, why don't we have more innovation when it comes to traffic signs and signals? Is there a consensus we're working with the optimal set?