I too have long had the feeling that metadata could be applied more effectively in many different areas.

I floated some vague Perl testing metadata ideas in Perl CPAN test metadata -- though it didn't generate sufficient interest to provoke me into pursuing it further.

Defining "standard" names for metadata seems helpful yet requires collaboration and cooperation from others. It's annoying when different folks use different names for essentially the same metadata. You might have a go at proposing a standard naming scheme and standard names for the project metadata you find useful.