A single place to see all incoming message
It's currently very hard to see which messages are unread, you have to find all conversation and team channel written in bold in 2 distinct tab.
It could be find that the Activity tab or a new tab name "Recent" list all conversation and team channel in a same place ordering them with most recent on top.
Very good idea!
Samepage has a very useful 'inbox' that lists all activity chronologically. It has been added recently and saves a ton of finding out where updates are.