Via Brian Beutler, Michael Rubin extolls the benefits of political reform in Iran for American national security: "An Islamic Republic accountable to its own citizenry would invest in better schools, hospitals, wages and infrastructure, and it would not divert billions for uranium enrichment and ballistic missiles."
Of course one might think that a United States of America accountable to its citizenry would invest in better schools, hospitals, wagesm and infrastructure rather than diverting billions for defense but that's not actually the case. And of course the opposition political party isn't proposing to divert defense spending into domestic investments to any substantial degree either. The unified security budget project has toiled away for years arguing convincingly that if we refocused our security spending away from such a heavy reliance on the Pentagon we could both save money and enhance our national security, but it hasn't been something that politicians are interested in.
What's more, viewed realistically insofar as the Iranian nuclear program has a military rationale at all, the rationale is that a nuclear weapon is a good way of defending your country on the cheap. Pakistan couldn't possibly afford to keep up with India in a conventional arms race, but a smallish nuclear weapon gives you a ton of deterrent power. The Iranian regime sees itself as beseiged by threats -- located in a dangerous part of the world, subjected to unprovoked US-backed invasion by Iraq in the 1980s, and now with American troops in Afghanistan and Iraq. They could try to build up a conventional military that could challenge the US, but it's probably cheaper and easier to try to build a nuclear weapon.
Similarly, whether or not Iran's interest in at least obtaining the capacity to build a nuclear weapon wanes is probably going to have less to do with the form of government in Iran than it will to do with perceptions of the security environment facing the country. Iran feels insecure, and also feels that the Pakistani and Israeli nuclear arsenals make the NPT regime a bit of a joke. To get the Iranians to verifiably disarm, something's going to need to be done about one or both of those factors. Different people will have different perceptions, so changes in personnel at the top of government in Teheran would make some difference but it's not automatic.
Photo by Flickr user Hamed Saber used under a Creative Commons license