I wonder if Disney, which built its empire on repurposing public domain Hans Christian Anderson stories as animated films, would have agreed with your assessment.
The value of the public domain isn’t in its literal resale, nor is it supposed to be: the value is in being a direct, continuing, and explicitly legal source of inspiration for the new.
Indeed the Arden Shakespeare show you how to make money (as does Disney): it’s the value add. Translation, curation, commentary, re-interpretation, analysis.
Contrast with books written in the seventies that have neither huge followings nor electronic versions: they might as well not exist.
Reclam would like to have a word with you. For the non-Germans here, they are a German publisher known for their iconic yellow editions of literary classics. They got their big break in 1867 when Faust entered the public domain; their Faust edition was a cash cow, and they continued on with other authors. Later on they branched out with their own stable of authors.
I'm not saying that the intangible benefits don't exist, but even from free material you can make money.
People focus on the biggest of the big as if that solves anything.
The Shadow debuted in 1930, so it is also not yet in the public domain, but was also in a movie as recently as 1994, and it still appearing in licensed comics in 2015 and ongoing.
Some Tom Swift books have entered the public domain, but not all, and the character is still covered under trademark law also.
You're making a great point about how copyright is too long, leaving characters to languish, but none of your examples are actually in the public domain.