It seems GitHub has begun implementing support for modern Python dependency metadata, so Hatchling now implements the metadata methods Implement minimal versions of metadata preparation methods by ofek · Pull Request #466 · pypa/hatch · GitHub
As I mentioned in this thread and here and elsewhere, any builder that has build-time hooks like Hatchling and setuptools cannot technically keep PEP 517’s promise e.g. C extensions would require different tags in the WHEEL file.
I now consider the methods as mostly being for non-frontend tools like tox and Dependabot. So Hatchling only writes the METADATA file to the metadata directory and continues to ignore that directory itself.