I've been thinking a lot about the Bechdel Test recently, and absolutely echo your concerns about using it "as a sweeping determination for whether a movie is inherently good or bad." I don't believe this was the intention of the test, and I am with you in frustration that it has been distorted in this way. There are powerful stories to be told that don't involve women, and likewise that don't involve men. And, as you note, passing the test is not necessarily related to how empowering or demeaning a movie is to women.
However, I do think the Bechdel Test is useful as a (very approximate) gauge for which voices are being heard in any given story, and in the balance of stories told overall. It is really disappointing to me, as a woman, when the most interesting and three-dimensional characters in a story are all men while the women merely talk about what the men are doing. Bechdel-testing one movie doesn't tell us much, but if we look at the percentage of movies that fail Bechdel in a given time period, it can be one indicator of how the studios are doing at portraying complex female characters.
What I think is really interesting is when I think about an opposite Bechdel Test (maybe one exists? if so, please enlighten me!). How many works of fiction exist that DON'T have two men speaking to each other about something other than a woman? I don't have an evidence-based answer to that question, but by anecdotally pondering, I'm having trouble identifying a single one (ignoring any all-female casts, as I would give the same pass to an all-male cast and the Bechdel Test).
As a society, I do think the male voice is still the default. And Bechdel is one small piece (however imperfect and incomplete) of understanding our reality and moving towards a more inclusive future.
@MerlinTheGoat I find your commentary nuanced and thoughtful, and I think we agree on many things. I've been a long time lurker on these forums, and yours is one of the voices I have come to value over the years. Just wanted to add my two cents to a topic that I have been personally pondering lately.