Using Classic Outlook on Windows for personal email, calendar, and contact management
Here's a specific scenario that is broken by this change: Inbox Zero
Precisely my problem. I use the slightly different, triple A folder structure of Action Required, Awaiting Response, and Archive for inbox zero, but this is the issue. Not being able to see the totals in these three folders, at a glance without having to check them by manually clicking or hovering*, is a fairly significant efficiency cost.
If it helps you, I have set mails to not switch to read automatically. So effectively I have the same functionality so long as I don't pop them out where they become read. Periodically I set the contents of each folder to unread to be sure. It's an imperfect solution but it has allowed me to minimize the disruption caused by this missing feature.
*bolding this because hovering the mouse is continuously being put forward as a solution despite the fact it doesn't work for this method.