Reid has Romney where he wants him. He's showing just how little in taxes the guy is paying in comparison to the "middle class" which sometimes pays 35%. Romney can cry about the raw figures as much as he wants. However some people will only look at the percentage he pays vs the percentage they pay and wonder why he keeps a higher percentage of his wealthy income than they do. People are eventually going to start demanding he pay a higher percentage because he can afford to far more than they can. It's as good a political chess game as I've seen anybody play and Romney is pretty close to being check mated.
This isn't the Obama birther thing. There is definitely political fallout from releasing these documents. Which is why Romney is in a tough position. Obama released his birth certificate. And what? It made birthers the laughing stock of the crowd. Romney releases his tax returns and the majority of Americans will take notice of just what percentage of his income he's "forced" to live with vs what they are forced to live with.