I don't think this has anything to do with sensible minds and more with strategic minds. Like I said this is a bold move for Iran and they must believe this attack leads to a success of some kind. Such as if the Saud's don't respond then we see a big shift in power and this could lead to a big change in the ME and all accomplished with a bold move but without a war. This might be a game changing move by the Iranians?
The problem with a war between these two nations is they have no shared land border and small navies. If Iraq allows either side to use its territory to launch an attack on the other its in another war. So how would they fight a war? Unless either side wants to risk a water borne invasion with their Armies it would be a long distance war of aircraft, missiles and probably special forces who would destroy each others oil infrastructure trying to take away each others revenue.