So, we're not going to change the end-game, we're just going to piss of Iran....and you think that's good?
Consider things from the Iranian's perspective. Back in the day, they were establishing a legitimate democratically elected government. The US overthrew that government and pushed a brutal dictator into power, who tortured and murdered many Iranians. From their perspective, the US is an evil nation that does evil things. Nuclear weapons look like the only thing that could give them security against the US. And we're hellbent on stopping them. Heck, the US has never even apologized for overthrowing their government and installing a murderous dictator: can you really blame the Iranians for believing that the US government is trying to screw with their country?
The only way this ends well is with a deal and deals require trust. Does Stuxnet promote that trust? Or does Stuxnet just provide further evidence that the hardliners are right, that the US is trying to screw with their country?
industry figures out that they need to lock down their machine controllers
This seems like wishful thinking. We have a terrible track record of getting large scale systems secured, even in areas where those systems are under continuous public attack. Industrial software is not one of those areas, so developers of such software are unlikely to take security very seriously. But even if they did: we don't know how to get them to build secure systems.
Microsoft spends a huge amount of developer time and money on system security. They're not very successful. But they devote a much larger fraction of their budget to that goal than any industrial software shop. So expecting industrial software shops to produce code that is even as secure as Microsoft's seems...unlikely.