I'm really not surprised at this poll outcome given the tenor of our times. Democrats and the media have been pounding away for decades with the idea that if it's good for rich people and corporations, it's bad for you. And very few Republicans have offered effective rejoinders to this idea since Ronald Reagan left the stage.
The frustrating thing is that Republicans have done so little to make the case in the run-up to the current bill being voted on, which means they're essentially shoving a much-improved tax code (although not nearly as improved as it could have been) down the throats of an unenthusiastic nation that doesn't really see why it's necessary. You can blame people for their economic ignorance, and I do, but really, where have the voices been for the past three decades or so making the case for these policies? Jack Kemp? OK. The Club for Growth, kinda sorta. Herman Cain? You had your chance, people . . .