> Also, the books have a quaint 1940s (NOT 1950s as people usually say it) atmosphere ...

    The next day’s hearings were entirely different. Hari Seldon and Gaal Dornick were alone with the Commission. They were seated at a table together, with scarcely a separation between the five judges and the two accused. They were even offered cigars from a box of iridescent plastic which had the appearance of water, endlessly flowing. The eyes were fooled into seeing the motion although the fingers reported it to be hard and dry.

If you've got a copy of the ebook, search for "cigar". The use of tobacco as a way to demonstrate luxuries beyond the regular is there.

In a recent re-reading of the series, I started having difficult with it in Second Foundation... and forced myself to finish Foundation's Edge. The amount of psionic ability and the... for lack of a better word "preaching" with the monologues was very much a science fiction of a different time.

Foundation (the TV series) had to do updates for modern audiences and media. I'm not sure if trying to remain perfectly faithful to the books would represent them well.

Foundation is a soft sci-fi about interactions between individuals and history and society. Trying to maintain the incidental harder parts of the written works that modern audiences expect to be somewhat consistent of far future technology with the 1950s lens on them would be quaint and a bit off-putting to people expecting future tech.

    He threw his cigar away and looked up at the outstretched Galaxy. “Back to oil and coal, are they?” he murmured—and what the rest of his thoughts were he kept to himself.

They took the major points, and wrote to follow the general path from one point to another given the expectations of an audience consuming it often for the first time - 80 years after the original was written... and given constraints of the format and continuity of actors (60 minute episodes rather than as a chapter of a short story in Campbell's Astounding Science Fiction).