It would be nice to have a temporary 'beta' mode which could beYour observation is a little bit off-topic, the topic being the Find a group (directory) listing - and a group can be switched between listed and unlisted at any time. Nevertheless, you've hit one of my pet peeves so I'll change the subject line and roll with it.
It's like being forced to name your child at conception with noGreat analogy, and I agree. Having these "one-way traps" (you cannot open the group's archives to non-members once they've been restricted to members-only) are an impediment to group formation, and a real source of friction and confusion for novice group owners.
Perhaps it could be allowed as long as the owner was the only member,Since the avowed purpose of the restriction is to protect the privacy of member's content, allowing the archives to be opened to non-members as long as the owner is the only member makes a lot of sense.
I'd go further and allow the archives to be opened to non-members as long as the only postings in the archives were made by owners or moderators; or are older than the date/time the archives were last made members-only. The first condition would allow having a larger team work on the start-up of the group. The second condition would allow an established group to correct an accidental (or malicious) switch to members-only archives - perhaps at the cost of deleting a few messages that arrived after the switch.