When working in the inbox you would like it to help you. Imagine if you automatically could create tasks,calendar appointments from certain incoming emails.
Perhaps create documents in the notebook template to store interesting newsletters.
a more intelligent inbox that can automatically do stuff for you and just leave a summary in the inbox for you like the out of office summary would be a great help to everybody that receives alot of emails.
Googles approach with the priority inbox, that sorts the emails with different priority depending how often you send / read emails to a recipient is also very interesting but that will probably only solve a little bit of the problem.