Well if we failed to kill him 60+ years of political assassinations would probably go differently, as his was the first big goverment-planned killing.
This has always bothered me, the concept that he was somehow a political figure, and that his demise at the hands of American fighters is some sort of assassination. This is, simply put, ludicrous.
Yamamoto was an ADMIRAL, an active serving officer with a field command, He wore the uniform, not as a show, but because he was a career military man. In war, the whole idea is to kill the guy in the other uniform. It is especially useful to kill enemy officers, the higher ranked the better (it is no accident that saluting is forbidden by the U.S. military in hostile fire zones) since they have a greater impact on the battlefield. The term for this is "force multiplier". Had Yamamoto been on the deck of his flagship, the
Yamato, when a bomb hit her, his death would raise no comment, even if the only way the U.S. found the ship was with decrypted code data.
It seems that there is a belief that the U.S. did something "wrong" by shooting his bomber (wait, a bomber, isn't that a warplane

) down on a designed mission, or set some bizarre precedent by killing a sailor during a war. For in the end, that was who Yamamoto was, a sailor, a high ranking one, who was famous, but still a sailor, nothing more, nothing less. He was not a member of the Japanese ruling junta, never had been a member, and was not even a candidate to become a member.
The really funny thing is, had it been General Tojo, who WAS the leader of the Junta, that the U.S. shot out of the sky, no one would have cared, then or now.
Whole thing makes no sense.