Reading a couple of takes on the political themes of The Dark Knight Rises from Ross Douthat and Jamelle Bouie, I think the latter goes a bit too quickly to the idea that TDKR is a mere critique of radicalism.
One of the signature elements of American life in 2012 has been the mainstreaming of concern about income inequality. Lots of people who don't think of themselves as political radicals are upset about it. That probably wouldn't have been the case in 1972, when the baseline level of income inequality was much lower. And part of what's going on in TDKR is an effort to eliminate the kind of Paul Krugman / Tim Noah / Barack Obama "I'm a liberal, but I'm worried about inequality." Instead, an Occupy-esque level of discontent that the rich are "living so high and leaving so little for the rest of us" is voiced by a thief (you're not going to find Krugman writing columns about how property is theft) and then dissolves into the madness of Bane-ism.
Bruce Wayne, meanwhile, is genuinely a good guy. He's rich, but his eyes are open to valid critique of other rich people. He blames them for throwing charity balls at which too little of the money goes to actual charitable purposes. He's concerned about unscrupulous business practices of others. But he certainly doesn't think that inequality per se is morally problematic, and the charitable work we see him directly involved with is the classic noblesse oblige cause of orphans. Crucially there's not even a question of whether Wayne deserves to be rich because he's a "job creator" or because he "built that"—everybody knows he hasn't done anything to get rich, but the appropriate response is to be a responsible steward of his riches and his family's legacy rather than to level the playing field.
The point here is less to criticism radicalism (about which people have their opinions, come what may) as it is to criticize the new moderate egalitarianism by suggesting that it's more radical than it seems. The question is do you want to overturn the existing social order or do you want to defend it against the forces of chaos? If it's "unfair" that the people in the top position have so much, then it seems like you do want to overturn it. But that's radical. If it turns out you're really just sad that orphans are going hungry, then that's consistent with the status quo. But the solution is basically to persuade wise stewards of the status quo that it's in their interest to feed orphans rather than have needy teens ending up in the sewers recruited by Bane.