What do you think the media reaction would have been if Obama had refused to release his tax returns? (Or Clinton, if you will.) Do you think the issue would have essentially vanished by now? Remember, this is the same Liberal Media that hounded Clinton for years over Whitewater and a blowjob.
Likewise, what if Mrs. Obama (or Mrs. Clinton) had said "We've given all you people need to know." What reaction do you think that would have gotten? Especially the dismissive "you people"?
Does the treatment of Romney over this issue really strike you as balanced? Do you truly believe that his tax returns are a non-issue, in the face of forty years of standard behavior for presidential candidates, as initiated by Romney's own father when he ran for president?
And do you think if Romney is elected, we'll see a "Taxer" movement the way we've seen a "Birther" movement?
I don't suppose we'll ever know what was so dreadful that the Romney campaign thought it was worth withstanding the pressure they did come under. Luckily for them, no one really cared in the end. They gambled and won on this issue in a way that no Democrat could ever have gotten away with.