I appreciate you've taken the time to consider what we've designed here. A lot of thought as definitely gone into it.
I like your naming of 'List View' vs 'Thread View' 💯
What you proposed for 'single message' is something we intend to do in an upcoming version. It's needed for when you single out a message, so you have full context. The current single message has always been challenging on context.
Something tells me you've designed websites/apps before? 🤓