On "The Sea Raiders" -- there may be a reference to this in some of his letters; I don't recall if he mentions this one specifically, but he did talk about Wells and his reaction to his work in a way which probably explains his
not mentioning this one in particular.
As for the Ellison story -- well, it was somewhat "Cold War-esque", as it was written in the middle of the Cold War, when many of the concerns behind the tale were particularly high -- especially about the stupidity of either or both sides continuing to escalate the technology of destruction without regard to human life (recall the neutron bomb, which was supposed to destroy organic life, but leave structures intact, for instance). You cite "the computer" and say you know "how it was meant" -- there have been varying interpretations of this story over the years, so I'm curious: what do you have in mind there?
In this case, I would hardly agree that such points harm the tale; rather they provides its center. Ellison does sometimes write a tale just to entertain; but in general he's a writer very driven by moral and ethical concerns, which he conveys with great passion.