That Romney wasn’t better prepared for the attacks on Bain and the questions over his taxes is one of the great mysteries of this campaign. An example: In 2008, Romney turned more than 20 years of his tax returns over to the McCain team in order to be vetted for the vice presidency. So he clearly realized that tax returns could matter for political campaigns. And yet he didn’t call his accountants in 2008 and say “make my taxes simple. Now.” Why?
What isn’t a mystery is why he isn’t releasing more of his tax returns now. As John Cassidy writes, “It’s only fair to assume that Mitt is doing what he always does: acting on the basis of a careful cost-benefit analysis. [George] Will’s comments on this were spot on: ‘The cost of not releasing the returns are clear,’ he said. ‘Therefore, [Romney] must have calculated that there are higher costs in releasing them.’”
If anything, this is even more mysterious than Ezra suggests. Romney lost his 1994 Senate bid at least partly because of Ted Kennedy's devastating attacks on Bain. In 2002 he won his race for governor, but he got beat up pretty badly over Bain by Shannon O'Brien in the process. In 2008 he had to defend himself against Bain attacks again. In 2012 Bain haunted him yet again during the Republican primaries. So it's not as if he was unaware that Bain is a problem. Why does he still not have a better defense?
As for the tax returns, I don't know what the deal is. Here's my latest guess, though: there are probably multiple years in which Romney paid no taxes at all. This would very definitively be a Bad Thing, so he really doesn't have any choice but to take the heat instead. A multi-gazillionaire paying no taxes would open up a can of worms way too big not to choke on.