While it is rather trivial to implement the proposed functionality - all that's required here is to eliminate the check for __init__.py from pkgutil._iter_file_finder_modules - this would have undesired impacts on, e.g., pydoc.apropos:
This function would then recursively report *any* directory/subdirectory on sys.path, which is quite surely not what people want.

I think this is a fundamental problem with namespace packages: they are nice and flexible for specific imports, but they make it impossible to know whether a directory found on the filesystem is *intended* as a Python package or not.