No one wants war. But the people with whom we deal in the ME, and throughout the world only respect strength. They take advantage of weakness and push their nefarious agenda as far as they can. Failure to respond is an invitation for them to proceed to more dangerous action.
Oh I completely agree that sanctions are unlikely to change their behavior. But we must realize that a full scale war against Iran in todays environment would not turn out well.
As much of a mistake it was to overthrow other dictators in the Middle East has been, supporting a popular uprising that leads to the overthrow of the Iranian government may be the least bad choice. Sanctions are part of that strategy.
Bombing their nuclear facilities is another path. This would likely occur after Iran attacked one of our ships in the gulf. Big risk here once again.