If viewing the number of read and unread messages in all of your folders at one time is so critical, just open the Folders screen in another browser window, so you can view the message counts while you are doing anything else. For example, what if you want to view the folder counts while you are composing a message? You can do this with the classic interface as you are describing. To open Folders in another window in Firefox:
- While viewing the main message screen, right-click Inbox and choose Open Link in New Window.
- In this new window, click the Create or edit folders link at the bottom of the folder tree.
- Resize this window. It shows all of your folders and message counts. The counts will automatically change dynamically when new messages arrive.
If that's not good enough for you, choose some other email provider. But I doubt you can find one which shows the folder counts in this way in their webmail interface, so in my humble opinion that specific feature isn't very popular.
Bill