There is a curiousity factor to the '40's serials. I can't help but squint and wonder what might have been been with a bit more money, resource and dedication. But that would have been bucking the trend of how comic books were then percieved.
Zorro, an influence on the development of Batman as a character, does give some indication as to what could have been done if Batman had been taken a bit more seriously. There are also a good number of thriller, adventure and horror films of the 1920s, '30s and '40s that give you an idea of what could have been done.
I also look at the first season of The Adventures Of Superman
with George Reeves as something of a template to how a more straight and somewhat more serious Batman could have been done.
It really comes done to someone's vision challenging current accepted conventions. Superheroes on film really didn't get serious minded until after the comics themselves had done so.
A fan looks at a favourite character and can express his appreciation to it being treated seriously. A non-fan will look at the same work and deride it for appearing to take itself so seriously.