Oldest SF not necessarily most dated?

While all SF from 30's, 40's and 50's is dated in obvious ways, it is
1970's SF I find most jarringly dated. One example is John Varley's
"Titan". Granted, one dated trope is technological -- 7-person
space****p arriving at Saturn apparently without a single unmanned
probe preceding, -- but what strikes me most is the very "1970's feel"
to the book. Free love and widespread drugs. Everyone on board the
****p sleeps with everyone else (in series, not at once) except for two
clones who are in an exclusive *****uous lesbian relation****p (that's
a mouthful!) -- and *NASA is described as prudish*! Apparently because
NASA prefers the above facts not to be known to public. And if you
think that streches the belief, cocaine is not only legal, but is
allowed on board. I doubt any publisher today would touch such a book
with a ten-foot pole for that reason alone.

Greg Benford's "Into the Ocean of Night" was also written in 1970's,
takes place in 1999, and to me is equally jarring. Chronic shortages
of oil and clean water, famines in India, three-corner marriages taken
for granted, etc.

Does anyone else feel the same way?