I'd say people who toook tha AF/Amex are not interested in the Amex benefits, as the requirements for the Gold card weren't well below the regular Amex Gold. I guess most people who took it were either actively going after the miles beneifts, or enrolled for the free miles after being talked into it by an Amex seller at an airport booth.

People from the first category will undoubtedly make the same calculation as we did: it's not worth it, and even if they don't know that Gold card is free (because they never asked for it, and never read this forum to know about it), they can't possibly value 6 miles/€ spent at AF and 2/€ more than the price difference. I did calculations about the Gold card and found the yield to be extremely low after April's Fool devaluation for most common redemptions options, and that was calculating a 110 € fee vs 10 miles/€, so an additional 400 for 2 miles... clearly it's not worth it.

People from the second category either won't have a gold card anyway, or won't spend enough on it to make it valuable. The last category would be those among them who would want a "true plat card" AND won't read the small print to realize they don't get the whole deal? I am not sure they make up a big part of the Gold cardholders, but I could be wrong.