Actually the strategic bombing in WWII was an outgrowth of the thinking of Billy Mitchell among others and was based on the idea that you could defeat a opponent primarily through airpower alone. But thats enough of a digression.
I guess if I was to lay it out, I'd say that
a) the blocade (including supporting landings) was a useful tactic for the North although not a war winning one. In other words you could have one the war without a blocade and with an invasion while the opposite was not true. This is true in the game as well.
b) that the coastal invasions not done for purposes of supporting the blocade were a mixed bag with some being much more successful then others. Overall, when taking into account the capture of New Orleans it was a win for the North and a good use of resources.
c) That the North used its massive Naval and riverine advantage well.