It'd be wrong if he was breaking laws. And I don't necessarily think Obama is leading the charge against Romney's tax return, considering his Jay Z parties.
I don't think people rail against the rich because of the loopholes. They do it because of insecurities over their own wealth and what the majority deems to be "fair." As a voting public, we could always just elect representatives who wanted to pass tax reforms, but we don't just in case we end up in that top 1 percent.
It's kind of similar to the South antebellum. Only 20 percent of people owned slaves, but the other 80 percent didn't want to limit the ability of the rich to consolidate more and more wealth because they hoped to also own slaves one day. They could rail on all day about unfairness and bourgeoisie, but at the end of the day, they'd prefer the guy who owned slaves as a leader.
I certainly don't fault either candidate for using advantages they have in the tax code. The public policy concern is how the shift in the tax code affects sending power and job creation. I honestly don't think more money in the hands of "job creators" who have a lot more than they have ever had is as stimulative to the economy as money in the hands of people who have to work for it. Certainly we need both capital and market demand. But right now I think market demand, not capital, is the choke point on the economy. Giving big breaks to big capital while taking away the mortage deduction from homeowners is exactly the opposite direction of good tax policy in my book.