Similarly moving on to a decent issue tracker, Jira’s support for Epic’s/stories/tasks/capabilities and its linking ability is a huge simplifier for long term planning.
Modern ticket system or issue tracker? Yes, absolutely. But Jira? Certainly not, considering Atlassian's business practices. A project like Linux deserves a system where they can maintain some control and it probably should be open source.
Yeah email is ancient and certainly terrible from a usability perspective if you're an outsider to the workflows, but at least it can't be shut off or taken away on a whim. Also it's universal and therefore accessible.