The reason to bomb Iran (from Steven Ruggles - it might allow a boost for whichever Republican candidate best suits Bush. It would require a hell of a boost, but I'm sure if the media pundits have enough orgasms over the event, it will do the trick well enough for the Diebold factor to look plausible.
The reason not to invade Iran - Congress is already shovelling the maximum amount of US taxpayer money (or, rather, US taxpayer future money) towards tax cuts for the rich and government contractors that it can. It doesn't need another reason - such as sending soldiers to occupy yet another chaotic clusterfuck of American creation where they are not wanted. Iraq is quite adequate for that.
Reasons not to be cheerful, part 1 - the range of the Chinese Silkworm (obsolete now) is 95 km. The Straits are 21 km wide at their narrowest.