I'll keep it simple.
- No direct loss of life due to sanctions. (Good for the West as well as Iran.)
- Does not stretch the US military
- Keeps costs down
- See point 1
- Palatable to the US community that fears US belligerence
- Appeals to the world at large that feared that the US just knows warmongering as its foreign policy tool
- Sanctions do not enrage Iran's key allies, which include China, Russia, and India. (Yes, these countries consider themselves Iran's allies. Want WW III?)
- American retains a foreign policy that is not dependent on Netanyahu's blood-thirsty whims.
- The damage resulting from sanctions is ongoing, and is difficult to reverse
- This is key: Iranians will blame their government for ills, not some country (like America) for dropping bombs.
- This is key to fomenting an internal revolution where the youth take charge.
- The US wants this passionately. It is the best way to "flip Iran" to being less belligerent.
- Iran is a huge country.
- It has a population of 75 million. It is 1/4th the size of the US in terms of population.
- Its population is significantly younger.
- Remember, nothing angers a powerful population more than being attacked without valid cause. The only valid cause is being belligerent, not the threat of belligerence.
- It is hypocritical by international standards for Israel to have nuclear weapons, while Iran cannot.
- Israel, along with India and Pakistan, has not signed the NPT. Even China has signed this.
- Also remember, nothing is more powerful than economics when swaying a population. Break the economy, break the people.
