[mbreese]

I think you're missing the major aspect of mailing lists that is why they are used for projects like Postgres or Linux: transparency. (at least when the lists are also archived, which is a different issue).

Mailing lists lets the future user see the decision making process unfold throughout a thread. These interactions can be archived and searched. Most users don't interact with these mailing lists in realtime through an MUA. They search an archive to find the appropriate thread. And critically -- anyone on the list can build the archive. It doesn't require any special infrastructure on behalf of the list owners.

It can be cumbersome, but it's also robust. Imagine if the history was only present in bugzilla, Jira, GitHub issues, or a forum? Bug trackers aren't always the best way to work through a brand-new API design. Email back and forth with collaborators on the other hand...

Also -- mailing list archives are also ridiculously easy to index in a search engine. Data stored in bug trackers aren't always as simple...