As the Python Packaging Index (PyPI) has progressed, the Python Packaging Authority has shifted from recommending the distribution of packages on PyPI to requiring distribution via PyPI by default. The latest version of pip will not install a package except from PyPI without a special parameter (https://github.com/pypa/pip/pull/1055).
As a result, official releases of comtypes should be made available via the PyPI page.
I'd be happy to help support this - just add me as a maintainer on the comtypes PyPI project.
This ticket is fixed, looks like it can be closed.