Mitt Romney’s campaign, as promised, released the former governor’s 2010 tax returns, as well as an estimate for his 2011 returns, and we’re starting to get a sense of why the Republican candidate wasn’t eager to share these details.

Mitt Romney offered a partial snapshot of his vast personal fortune late Monday, disclosing income of $21.7 million in 2010 and $20.9 million last year — virtually all of it profits, dividends or interest from investments. None came from wages, the primary source of income for most Americans. Instead, Romney and his wife, Ann, collected millions in capital gains from a profusion of investments, as well as stock dividends and interest payments.

By any fair estimate, over $42 million in income over two years isn’t bad for a guy who jokes about being “unemployed.” Indeed, Romney would be in the top 1% based solely on the income he makes in one week.

Romney said last week that his rate was “closer to 15%,” but as it turns out, despite his vast wealth, he actually only paid a 13.9% rate last year — lower than his political rivals who aren’t nearly as wealthy, and lower than most middle-class American workers.

And what about those overseas investments?

His 2010 return also showed that he had a financial account in Switzerland that was closed in 2010 and that he generated income from overseas investments. He also reported financial accounts in Bermuda and the Cayman Islands.

A Reuters report added that Romney’s Swiss bank account was closed in 2010 “after an investment adviser decided it could be politically embarrassing to Romney.”

I suspect those with far more expertise in this area will subject these materials to considerable scrutiny, but at first blush, the disclosure appears to raise at least as many questions as it answers.

Why did Romney set up $100 million trust funds for his sons without paying any gift taxes? Were his accounts in the Caymans and in Switzerland created to avoid paying taxes? Was the closing of the Swiss account related to this IRS investigation? And given all of the questions surrounding Romney’s Bain-era work, why does the Republican candidate continue to insist he won’t disclose returns from previous years?

What’s more, following up on a point from last week, even if Romney argues that he’s simply playing by the rules — taking advantage of existing tax loopholes to pay lower rates than much of the middle class — this doesn’t explain why Romney is eager to exacerbate issues on tax fairness with his tax plan that makes the problem worse.

In a debate over tax fairness and income inequality, Romney is practically a case study for What’s Gone Wrong, but he can at least plausibly argue that this is a mess he benefits from, but didn’t create. Romney, however, prefers to believe the problem doesn’t exist.

Greg Sargent did a nice job capturing the larger political context:

I’m not sure the Obama campaign could have scripted this more perfectly. In a remarkable bit of good timing, President Obama is set to deliver a State of the Union speech focused on income inequality and tax unfairness on exactly the same day that Mitt Romney will reveal that he made over $40 million in the last two years — all of it taxed at a lower rate than that paid by middle class taxpayers. […] Romney doesn’t just disagree with Obama on these fundamental issues; he personally symbolizes virtually the entire 2012 Democratic message. He is the walking embodiment of everything Dems allege is wrong with our system and the ways it’s rigged in favor of the wealthy and against the middle class. Yet this is the standard bearer the GOP seems set to pick.

Romney and his aides believe these materials should end the discussion. That’s backwards — the larger debate is just beginning.