Agreed, but since this is an aviation focused site the discussion has centered on aircraft. Overall, the bombing survey presents a fairly comprehensive review of what factors contributed to the victory over Japan. If you haven't read it, here is a link to the summary report.The bomber's advocate would point out that that blockade was itself greatly aided by B-29 mining operations. I do agree with your point, and think the submarine's contribution to our victory is always overshadowed by the Bombs being dropped.
I also came across this recently which is informative and talks about the overall war and air war against Japan in the last few months of the war:
As well as a good overview of the proposed invasion:
The casualty projections associated with an invasion of Japan vary widely and seemed to be based on whether the source was inclined for the invasion to happen or not. The accepted most likely projection assumed that the casualty rate for Okinawa was an accurate prediction for the first 30 days of the Kyushu landings and would have resulted in around 300,000 US casualties during that time frame.