Among "needed innovations", the post lists: "A good method for telling users what’s important to read and what can wait for later." To me, it's downright scary that someone would want Google telling them what is important in their own mailbox. Personal responsibility bad, Hand-holding good, apparently.
An important feature of Gmail from the get go was how well it separated Spam from relevant email. I don't think you'll find too many users who prefer to do that manually. It's a matter of degree of course, but scary seems too strong a word.
As I mentioned elsewhere: spam can be filtered objectively, but importance would have to be identified subjectively.