I agree with you that production value replaced plot, likewise most of my favorite Sci-Fis are from the 70s and 80s.
That's because of the market needs of cinema productions to appeal to a wider and "easier" audience, in order to have a guarantied return of investment.
As a result do TV and streaming productions often offer much better plots nowadays.
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery