On Channels and Groups:
For simplicity's sake let's think about two distinct group dynamics:
1. Public forum: anyone can immediately start posting, there is no concept of a member.
2. Membership group: you need to join first before posting. Each member can see each other. Even for a public group, people must first join before posting.
The current structure of Powping channels takes the form of a public forum, but there clearly is great value in the membership group format where members can see each other and interact in more intimate settings. This could actually serve a different purpose than the current channels format.
The reason channels were released in the form of a "public forum" was because it's the simplest to implement, open by nature, easy to participate, more privacy for subscribers ("lurking" is not a bad thing), and also easily extensible because of its simplicity.
These two group dynamics are completely different and serve different purposes. Comparing the two and saying one is absolutely better than the other would be like saying "Dogs are better than cats".
The goal is to facilitate various different dynamics including but not limited to both of the above options. In fact there's one new experimental feature already released out in the wild.
Finally, privacy is important, so no matter what privacy settings are added in the future, they will never be rolled out in a way that can betray the original expectation of the users.