This one is a more recent cover that i think is iconic as well.
It's a good cover, but it doesn't fit with the others you posted.
I think the cover is much more famous than the interior for that one.
Although this gets to an interesting problem, in that major issues are more likely to have iconic covers.
That seems to suggest it's more than just random chance, though a cover for a comic in which something big happens in probably going to be seen by more people than the typical cover.
People are going to be more exposed to the covers for ASM 238 and ASM 300 than to the typical Spider-Man comic, because of the significant first appearances.
Sincerely,
Thomas Mets