In terms of Iran, it is based on my personal experience there 1977-79, which included the overthrow the Shah and the hijacking of the Iranian Revolution by Khomeini. Iranians like many others in the Middle/Near East are believers in conspiracies and the ability of the West to manipulate events inside their countries. An overt and unprovoked attack, in their mind, would not be helpful to the forces advocating regime change inside Iran. Unless we are prepared to overthrow the current regime using military force, we would be aiding the mullahs by staging some symbolic military attacks, especially if there is any collateral damage killing innocent civilians.
You seem to equate not initiating overt military attacks against Iran as not doing anything. That's not true. There are other options.
NO authoritarian government has ever been over thrown without a credible external threat actively forcing the repressive Govt to change. Without a credible external threat, the authorization Govt has no reason to ever reform their system.
I believe you made this fallacious assertion before. Poland, Iran, the US, Tsarist Russia, China, Cuba, France, etc. are just some examples of authoritarian regimes being overthrown internally without a credible external threat forcing that government to change. Sometimes they are replaced by another authoritarian government. You underestimate the ability of people to overthrow a regime withiout "a credible external threat."