The US and most of the rest of the world think that Iran is an unstable country in an unstable region and that it would be a bad idea for all the countries in that region to have nuclear weapons to threaten each other with. Its a fair point.
So you think its a better idea to allow only one nation to ignore non proliferation treaties, have nukes and threaten its neighbors with it? Not just any nation, one of the only remaining apartheid regimes, a terrorist sponsoring state ran by warmongering crackpots that actually are crazy enough to use it offensively.
I saw a poll a while ago held in the middle east region about the issue. Almost no one there considers Iran a threat to stability or peace, quite on the contrary. Overwhelmingly they see Israel and the US as a threat to peace and stability. When asked if they would consider the region more or less dangerous if Iran acquired nukes, the majority now say it would be positive, even in Sunni states, go figure. Here, I only found these key findings:
http://www.brookings.edu/reports/2010/0805_arab_opinion_poll_telhami.aspx I don't think Iran can be stopped
They
have been stopped from developing nukes, if ever they did, nearly a decade ago. Why doesnt anyone listen to US intelligence agencies when they say something diametrically opposite of warmongering and lying politicians and media? Go read the national intelligence estimate.