Comment 9 for bug 334064

Cristian, even if the Launchpad developers introduced an option, they'd still need to choose a default, and then people would argue about what the default should be in exactly the same way as they currently argue what the behavior should be. More complex code, negligible benefit.

Besides, making it a per-user option would be a granularity error. It would make private replies extremely difficult, but whether a reply should be private or public depends much more on the message than on the sender.