I think Mac Man hit on something, that fans may respond to the Sci-Fi aspect of it.
If you look at it, I think that's the difference between SA DC & Marvel. DC comics and especially the covers have more of a "science fiction" angle to many of them (Flash, Green Lantern, Atom even the justice league - fogedebout Mystery in Space, Strange Adventures, Tales of the Unexpected, etc., etc.) while Marvel tended to deal with more social issues. Maybe why the older kids seemed to flocked to Marvel when I was a kid, with Johnny Storm goin' to college and Peter Parker's chick problems.
They're both great for different reasons.
Now we return to the regularly scheduled program