Hmmm... although I tend to agree, I think plenty of old sci-fi were packed with social agenda stoprylines, especially works by Heinlein, Bradbury and Clarke. Unless you're talking even older?

Most Sci-Fi is packed with social agenda. The space movies of the fifties preyed on our fears of communism (Attack by hostile aliens); the nuclear age (any movie with giant lizards, spiders, people, etc.); and the dangers of uncontrolled technology (Forbidden Planet, Angry Red Planet and others). Even sociological changes in the family structure were viewed through Sci-Fi (that dumb movie where the boy dreams that aliens are taking over parents and then he wakes up and the dream starts to become real; and another movie in which the teens, listening to an alien save the parents. Sorry I can't remember their names.)

But, if you want to check out some good old fashion space opera stories that have no (well, very little) social agenda, stories that pit man against mean old aliens that want to wipe out mankind or preserve him as a food source, then check out In Death Ground and The Shiva Option by David Weber and Steve White. People get eaten, ships explode and aliens get thwarted. It's cool! But don't read the last two books in the series (Insurrection and Crusade) unless you want some social agenda with your space battles!

S.M. Stirling has a couple of books out that are cool retro sci-fi... one takes place on Venus, the other Mars. It's an alternate history where aliens of some sort terraformed and then populated both planets with early humans, as well as all sorts of prehistoric flora and fauna... fun stuff.