As many Heinlein fans may recall, one working title for the book was "A Martian Named Smith".
Your comment echoes that of Orville Prescott ("disastrous mishmash of science fiction, laborious humor, dreary social satire and cheap eroticism.") , mentioned both in Vonnegut's review and at https://en.wikipedia.org/wiki/Stranger_in_a_Strange_Land#Rec... .
"Memorable" to you now is certainly different than 1990, when Vonnegut wrote, or 1961 when it was first released.
It was released at the start of the sexual revolution. American views on sex were already in flux - look at the reaction to the Kinsey Reports around 1950. Moreover, Heinlein timed the publication because "I had been in no hurry to finish it, as that story could not be published commercially until the public mores changed. I could see them changing and it turned out that I had timed it right." (Quote from that Wikipedia page.)
"The kidz" turning 20 now were born 40 years after the book came out, over a decade after the AIDS crisis, in a world where discussions about sex are much more common. Heinlein wrote Stranger "to shake the reader loose from some preconceptions and induce him to think for himself, along new and fresh lines" (Quote from that Wikipedia page.)
I think few kidz now consider mid-20th century ideas to be new and fresh. For that matter, how many young Asimov fans are there these days?
I don't much like Dune. However, I recognize the impact it had for its era, like its treatment of planetary ecology, written in the new Silent Spring era.
I think the same applies to Stranger. And I totally get not wanting to try to understand that era in order grok its context. ("Sure, you don't get it now, but after you watch the next five seasons it will totally make sense!")