Iran regime has been a great destabilizer and war monger. So, may be their nuke development just provided an opening for the regime change operation. The Middle East will be much more peaceful once Iran is de-fanged. This even may help Europe because Iran was helping Russia in the war.
no boots on the ground and more moderate goals. The current state of Iraq - severely corrupt moderately religious not threatening anybody kleptocracy would be a success here. Not threatening is the key - Iran has been behind sectarian violence in Iraq, behind Hamas, Hezbollah and Houthis, helping Assad, ... one can see that Iran's regime should have already been taken out yesterday just in order to advance peace in the Middle East.
Note - no boots on the ground wouldn't be a big limitation because in case of say ethnic violence, with Azerbaijani and Persian being the largest groups, or even just great social chaos, Turkey and Azerbaijan, are, as far as i understand, ready to bring their armies into the Iran's Azerbaijani populated provinces, which would leave Persians, who are many don't like that "Arab's Islam", in their provinces to their own devices, probably even restoring the monarchy with the Shah's son, which again would be a good outcome here.
They don't have much options. They have only Revolutionary Guard for them. Army hates the Guard. The Guard isn't really a fighting force, it can only launch missiles and beat unarmed protesters. Once it runs out of missiles (with a lot of missiles lost to the bombing), it is done.
I expect a full no-fly zone enforcement, and with that the regime's domestic authority and power will quickly go down the drain.
So we're blaming the US because Iran chose to pursue weapons-grade enrichment. Have you considered that Iran could simply choose not to do that, like every other paranuclear state?
Ultimately the choice of whether or not Iran gets to build a nuclear bomb is not up to them, and they're finding that out now.
What happened between Trump withdrawing from the treaty and Fordo getting bombed? I feel like you're perhaps missing a few critical steps on the Iranian side.
Trump signaled that diplomacy wasn't going to solve the tension, and they weren't getting what they wanted to in exchange for not building weapons. Of course they were going to build them. Why would they not, whether for offense or defense?
There are solutions other than war to nonproliferation.