The hero tale is one with a long history behind it. I think it's always been the dominant style. So that's not really a legitimate criticism...not unless you are making an encompassing claim, and if you are, then it's false. (I've encountered several books with a heroine.) And the dominant style always reflects the zeitgeist. (In the late 1940's and early 50's there was lots of WWII echoes, often re-staged in different settings.)
FWIW, my tastes have always been quite narrow, and minority, but I think they've narrowed over the years. OTOH, possibly it's just that the net doesn't provide exposure to the tales that I would like. Perhaps they're still out there, but I can no longer easily browse through and tell that they're something I'd be interested in.
Part of the problem is definitely the sales channel. Grocery stores only carry "best sellers". (They may not actually be best sellers, but they're marketed as such.) 20 displays of 10 books, and two or three with only a few...probably left over from last month.) Also a few books that I already have on my shelf, from a decade ago.
Even book stores lean in this direction, sufficiently that I no longer want to browse in them. (OTOH, I always preferred science-fiction and technical books.)
But I really think part of the problem is the zeitgeist. Nobody wants to read it. It's like when the anti-hero became "popular with publishers". People found reading that stuff unpleasant, so they stopped. Except for a few. And some of those will be picked up, eventually, as classics that everyone should read. Just like "Jude the Obscure" was. Nobody that I ever met liked that story, but some academics thought it was important enough to force everyone to read it.