So, Republicans had a choice. They could accede to certainty with Clinton-era rates on the rich, or uncertainty with Bush-era rates on the rich. They chose uncertainty. The Bush-era rates will live on for two years, after which nobody knows if they'll be extended or not.
For those still clinging to any naive notion that Republicans meant this as anything more than a slogan, the answer is now clear. They want low tax rates for the rich. They don't care about certainty.